KUWAIT, AUG. 2 -- A massive Iraqi invasion force stormed through this small Persian Gulf emirate today, driving out the government and taking control of the capital after meeting surprisingly stiff initial resistance from outnumbered Kuwaiti troops.

The Iraqi troops, who crossed the border at 2 a.m., quickly secured control of several key government ministries and spread their tanks and armored vehicles throughout the city. But they had to wage tough battles at several points during the day.

Reports from diplomatic sources late today said at least 200 Kuwaitis had been killed in the fighting. Other diplomats said it was impossible to get a firm figure, but they expected the total to be high. There were no reports of any casualties among the nearly 4,000 Americans living here or among guests in the capital's luxury hotels, some of which are in the areas where fighting was heavy early in the day.

{Iraqi soldiers rounded up and moved eight American oil field workers from their work places near the border of Kuwait and their whereabouts are unknown, an unidentified State Department official in Washington told the Associated Press.}

By nightfall, there was still sporadic fighting in some neighborhoods, and while Iraqi forces appeared to have consolidated control through much of the city, it remained unclear exactly how firm that control was.

{Iraq warned other countries not to come to Kuwait's assistance, saying in a statement broadcast on Baghdad Radio that its armed forces "will make Iraq and Kuwait a graveyard for those who launch any aggression." In Baghdad, motorists honked their horns and flashed their lights as Iraqis celebrated the news that their troops had invaded Kuwait, Reuter reported.}

Kuwait's ruling emir, Sheik Jabir Ahmed Sabah, fled to Saudi Arabia as the invasion was beginning, but his younger brother Fahd reportedly was killed defending the emir's palace, where some of the heaviest fighting took place.

Iraqi-controlled radio stations announced several hours after the invasion began that a new provisional government -- of Kuwaiti revolutionaries opposed to the ruling Sabah family -- had taken power. But continued calls to resist came from Kuwait television, which several Kuwaitis said was broadcasting from Saudi Arabia.

"Let them taste the chalice of death," Kuwaiti Crown Prince Saad Abdullah Sabah said in a broadcast.

The Iraqi invasion marked a brutal climax to what began as a quarrel between the two countries over oil money. Iraq's President Saddam Hussein accused Kuwait last month of violating OPEC oil-production quotas and stealing oil from a field shared by the two countries. When Kuwait refused to submit to Iraqi demands, Saddam sent troops to the border -- an initial strike force of 30,000 that grew to at least 100,000 by last weekend.

The invasion was widely seen by diplomats and Kuwaitis as an attempt by Saddam to gain control of Kuwait's oil wealth and install a compliant government that would respond favorably to his financial and territorial claims against Kuwait.

A more immediate prize for the Iraqi invaders was custody of 15 prisoners held by Kuwait since a December 1983 bomb attack on the U.S. and French embassies in Kuwait city that killed five people and injured more than 80. According to one Arab source, the Iraqis seized the 15 prisoners today and immediately transferred them to Baghdad.

Washington is extremely concerned with the fate of the prisoners because their situation and that of six Americans held hostage in Lebanon are closely linked. The hostages' Shiite Moslem captors have demanded that the prisoners in Kuwait be released before any of the Americans can be set free. Kuwaiti officials have steadfastly refused, saying that convicted saboteurs should not be equated with innocent hostages. How that stalemate might change with the prisoners' transfer to Baghdad was unclear today.

Western diplomats here reported that Iraqi troops were making their way to the southern part of Kuwait, and one said they appeared intent on going all the way to the Saudi border. Most of Kuwait's rich oil fields are in the south.

The British Broadcasting Corp. reported that Iraq closed its land borders today and revoked permission for its citizens to travel abroad. It also called up military reserves, reinforcing its 1-million-strong armed forces, the BBC said.

From an early morning overflight of Iraqi jets at 5:30, which alerted the city to the imminent attack, until late in the day, the boom of artillery shells and rapid fire of machine guns filled the air.

Some of the fiercest fighting occurred outside the emir's residence, Dasman Palace. It began about 6 a.m. and lasted until about 2 p.m., with an extremely intense 1 1/2-hour period around noon.

Diplomats and Kuwaitis also reported intense, prolonged fighting in the suburbs of Jahra and Riggae, where Kuwaiti military facilities are located.

The Al Shaab palace of the crown prince was burning late today, according to people living nearby.

The invading forces did not directly attack or seal off any embassies, although the British Embassy was affected by the fighting around Dasman Palace, which is only one block away.

The Iraqis, and the still-unknown new government they claim has overthrown the emir, announced a curfew early this afternoon.

As night fell today, tension and uncertainty settled on the city. "The situation is still very critical," one Kuwaiti said. This mood was heightened by the confusion created by conflicting statements about who was in control.

A communique broadcast simultaneously on Iraqi radio and television, and on a Kuwait radio station at about 1:45 p.m. claimed that a new "temporary and free" government had been established after the overthrow of the emir.

The communique accused the Sabah family -- descendents of a dynasty that has ruled Kuwait for 234 years -- of corruption and of violating Kuwaiti peoples' rights. It said it was "dismissing" the emir and the crown prince, who is also the prime minister, and would eventually "organize free, honest elections."

Iraqi forces, the communique said, had been invited into Kuwait to facilitate this transfer of power.

Kuwaitis who heard the broadcast said the communique was read by three different speakers, whose accents identified them as a Syrian and two Iraqis. They said the communique was aired on a different frequency from that used by Kuwait's radio station, suggesting that it was broadcast by a facility brought in by Iraqi troops.

Many Kuwaitis expressed ignorance of who might be cooperating with the Iraqis. Some speculated that they might come from among a section of Kuwait's population that has been denied citizenship because their fathers or grandfathers, although born in this country, were not able to prove it. They have been denied many of the financial benefits and access to top positions given Kuwaiti citizens.

This group, known as Bidoon, has been critical of the emir's rule, but diplomats said they were unaware of any feelings strong enough to prompt them to overthrow the emir by force. Kuwaitis said, however, that these people make up a large portion of Kuwait's military and security forces.

By late tonight, no Kuwaitis had come forward claiming to be part of the new government, eliciting skepticism among residents here that it actually exists.

"It's an excuse," said one Kuwaiti government worker. "I'm sure they are making an excuse for their intervention to give to their people."

"I cannot confirm such a government exists," a Western diplomat said. "It's clear the Iraqis claim it exists, but nobody has come forward and said, 'Here I am. I'm head of the new government.' "

Meanwhile, the channel that usually carries Kuwait TV displayed a picture of the emir and crown prince for most of the day, accompanied by a commentary saying they were the legitimate government and condemning foreign forces in Kuwait.

Some Kuwaitis said they believed the broadcast was coming from outside the country, since the national television station is in the Information Ministry, which was occupied by Iraqi troops early in the day.

The U.S. Embassy contacted most of the estimated 3,800 Americans in Kuwait today, telling them to be ready with their passports in case Washington decides to evacuate its citizens. That seemed an impossibility for most of today, as gunfire kept most people off the streets. Kuwait's international airport was said to be closed, having been bombed earlier by Iraqi jets.

In addition to the Information Ministry, Kuwaiti sources said that the Interior and Foreign ministries had been captured early in the invasion.

The invasion came less than 24 hours after talks between Iraq and Kuwait in Jiddah, Saudi Arabia, collapsed Wednesday morning. Their abrupt end came after Iraq reportedly demanded that Kuwait accept, without further discussion, Baghdad's financial and territorial claims.

While Kuwaiti diplomats in Washington and elsewhere appealed for military help Kuwaiti voices in this area, using a maritime radio frequency, sought help from the "Arab world and the international community."