The spread of political violence from Peru's southern mountains to the central squares of its capital is threatening to undermine efforts to preserve the country's three-year-old democratic government.

After months of increasingly bloody fighting in the isolated highlands of the Andes, the Maoist group Sendero Luminoso (Shining Path) has launched a new series of terrorist attacks here in Lima designed to weaken the elected government of President Fernando Belaunde Terry.

The terrorists have succeeded in imposing an atmosphere of high tension on this sprawling city. Coordinated bombings have caused blackouts of metropolitan Lima twice in the past two months, and a daring attack on the government party's headquarters two week ago left two dead and 32 wounded.

Tonight, a series of bombs exploded in Lima, blacking out several districts and injuring at least three policemen, authorities said. The officers were injured when a bomb was thrown at a station of Peru's special investigative police in the Miraflores district, police said. Other bombs exploded near a military barracks and the offices of Lima's University of San Marcos. There were unconfirmed reports of shooting incidents and civilian injuries elsewhere in the capital.

After several bombings here last Thursday, utilities were affected for three days, and government officials estimated the damage at close to $1 million.

The Associated Press reported from Ayacucho, southeast of Lima, that a 48-hour strike called by Shining Path, shut down much of the Andean city Monday.

The recent attacks came in defiance of a 60-day national state of emergency declared by Belaunde May 30. Police have rounded up hundreds of persons under the emergency--including more than 150 since Thursday--but have been unable to capture the top insurgent leaders or prevent the bombings of electric towers, factories and other government installations.

With more attacks now widely expected, Belaunde's government appears to be losing ground in its battle against the insurgents.

Few Peruvians believe that Shining Path has won significant support outside its ranks or poses a serious threat to the armed forces. But government supporters have become concerned that a failure to break the organization quickly could lead to increasing disorder in Peruvian cities or prompt a coup by security-conscious military officers.

The government's resources and populist image already have been badly strained by the battle with Shining Path, which has resulted in more than 1,500 deaths in the past three years. Courts and jails are staggering under the burden of hundreds of untried suspects, and poorly trained security forces have been accused of abuses ranging from illegal arrests to torture and indiscriminate killings of civilians.

Shining Path "represents the most effective way to destabilize Peruvian democracy," said Luis Bedoya, the president of the Popular Christian Party, which is allied with the government in Congress. "It is a kind of threat that our system is least prepared to handle, and it happens when we have not reached a clear consensus in Peru of what democratic institutions should do."

The threat of Shining Path to the government might be greater if it were not for the group's peculiar character. Formed in the early 1970s, Shining Path is perhaps the most dogmatic and secretive of Latin America's insurgent movements. Its leaders have made almost no effort at formal propaganda. They reject ties with all other leftist movements and profess qualified admiration only for Albania, of all foreign governments.

Despite frequent government claims that Shining Path is supported and supplied from abroad, diplomats and sources familiar with the guerrillas say there is no evidence of such ties. Most Shining Path recruits have come from regional universities or poor Andean villages, and the group is armed largely with stolen rifles and crude bombs made from dynamite charges. Its size, while believed to be 2,000 or less, is unknown outside the group.

For many Peruvians, the most frightening aspect of the terrorist attacks is the specter of nearby Argentina and Uruguay, where leftist terrorist and guerrilla movements led to violent campaigns of counterterror by military forces in the 1970s and years of authoritarian rule.

"The important thing is that there is an effort to prevent that Peru falls into the same situation as Argentina," said Mario Vargas Llosa, a novelist who is an increasingly active defender of the Belaunde democracy, "because it is very difficult to defend democracy in a country with a situation like this."

For now, even with a state of emergency in effect, Peru remains a remarkably free society. There is no curfew in Lima, no troops patrol the streets and strikes and political activity have continued despite the state of emergency. Press freedom is unrestricted, and leftist newspapers daily assail the government with bold-headlined accusations.

"This is an underdeveloped country and not a strong country, and democracy is weak and imperfect," said Vargas Llosa. "But you have to protect the imperfect democracy that we have, and Belaunde is doing everything possible."

Yet, many diplomats and other foreign observers agree with government opponents that the campaign against Shining Path so far has been inefficient and often unproductive, even as it has led to cases of repression.

Much of the problem, these analysts say, lies in the weakness of justice and security systems almost inevitable in a poor country recently returned to democracy.

"This is a country with limited resources, and the government has to work with what it inherited from a long military rule," said a Peruvian journalist. "You can't expect miracles."

Peru's court system, for example, is already so burdened with cases and complicated procedures that narcotics trafficking suspects have routinely waited two years in jail before their trials are completed. Now, with about 700 Shining Path suspects in jail on a variety of charges, the courts appear to be choked.

Although some of the Shining Path suspects have been held for as long as two years, no trial on major charges has been completed. Leftist government opponents have claimed that up to 300 of the 700 prisoners are leftists not connected to Shining Path and innocent of violence.

"There is a bottleneck that has paralyzed the system of justice for those people," said Enrique Bernales, a senator of the Revolutionary Socialist Party. "They are going to come out embittered and full of hate for the system."

Even more serious are the problems of Peruvian police and security forces. Anxious to avoid the political and tactical consequences of using the Peruvian Army against Shining Path, Belaunde attempted to handle the insurgents as a police matter until late last year. Even now, police are charged with most offensive patrols and fighting in the southern mountain provinces where Shining Path is strongest.

The various police forces have proved unprepared to handle guerrilla warfare. Traditionally ill-disciplined and poorly trained, even elite units have no expertise in sophisticated tactics and have been ill-equipped for rugged mountain terrain.

A wide range of political leaders say the police have failed in what should be their most important tasks, intelligence and preventive measures. Security officials conceded that they had not been able to penetrate Shining Path cells or anticipate attacks. The insurgents have been able to topple key electric towers in Lima repeatedly and even attack the government party headquarters without being stopped by police.

At the same time, the security forces have been charged with abuses ranging from illegal arrests to torture and indiscriminate killings, particularly in the area around Ayacucho, 250 miles southeast of Lima.

"Sendero knew exactly what institutions they would have to face," said Vargas Llosa, who headed a government-appointed special commission that investigated the violence in Ayacucho following the deaths of eight Peruvian journalists earlier this year. "We don't have Swiss guards. We have our sinchis police and Army. Of course there are abuses. You have to expect that."

Most disturbing for diplomats and other independent observers have been the hundreds of recent deaths in the mountain provinces around Ayacucho, where the Army has taken over political and military control. During April and May, the Army command severely restricted access to the zone while issuing a series of terse communiques reporting hundreds of Shining Path casualties.

The reports mentioned no wounded or captured insurgents, and in a score of communiques, only two police casualties were reported. When the reports raised public controversy and private diplomatic protests, the Army simply stopped issuing the casualty reports. Now, a diplomat said, "no one really knows what is happening out there."

Although no systematic evidence is available, leftist government opponents charge that police are visiting small villages and summarily eliminating civilians suspected of ties to Shining Path. Government officials, in turn, have sharply attacked both politicians and the media for reporting such charges, but have not provided rebuttals or investigated specific cases.

Many government supporters have called on Belaunde to create a special antiterrorist force, seek specialized foreign training for it and create special courts to handle cases in an effort both to reduce abuses and to increase the government's effectiveness against Shining Path. Privately, some recognize that abuses have taken place but argue that they are the inevitable price Peru must pay to preserve the overall democratic system.

Government opponents, in contrast, argue that the government's tactics are leading to a polarization of the country, the exclusion of political and economic solutions to the violence and the erosion of democracy.

Both sides seem to agree that for now, Shining Path has an advantage. Shining Path "is winning the political battle against both the government and the opposition," said Henry Pease Garcia, a magazine editor, "not in the sense that Shining Path is gaining mass support, but in the sense the political situation is turning out the way Shining Path wants it. There is no consensus on how to attack the problem."