MANAGUA, NICARAGUA, JAN. 22 -- Rock-throwing Sandinista supporters today disrupted an opposition ceremony, marking a rough start for what the government had said would be a period of new political freedom.

At midday, about 50 followers of the leftist Sandinista government hurled rocks and bottles through the windows of the headquarters of the opposition coalition, the Democratic Coordinating Group, during a ceremony to mark the first anniversary of an organization of relatives of political prisoners. Christian Democratic leader Agustin Jarquin was cut by a bottle, and two women from the group of prisoners' relatives were also slightly injured as the ceremony broke up in panic.

It was the first public opposition event since an almost six-year-old state of emergency was formally lifted Tuesday in compliance with a Central American peace plan.

The slogan-yelling demonstrators who gathered on the street outside the Coordinating Group are known as turbas, which, loosely translated, means "mobs." They are drawn from Sandinista neighborhood committees and labor unions.

The Sandinistas, mostly young people, denied that they had been sent by government officials. But several uniformed Sandinista policemen who arrived on the scene did nothing to halt the stone throwing and made no arrests.

The opposition politicians "are just a minority of rich businessmen who want to sell out our country to the contras. It's a provocation to the workers," said a 24-year-old construction worker, Jose Sevilla, who was among the Sandinistas. The U.S.-backed rebels fighting to overthrow the Sandinistas are known as contras.

Last week, opposition representatives held an unusual meeting in Guatemala with top leaders of the Nicaraguan Resistance, the contra alliance. Government security police arrested 11 opposition members for questioning about the meeting during the past week, then released them.

Today's scuffle began when a handful of opposition activists attempted to take down a banner hung by the Sandinistas in front of the opposition coalition headquarters. In a speech tonight, Bayardo Arce, one of nine members of the National Directorate of the ruling Sandinista party, accused the opposition of trying to hold a street rally without a permit.

Confusion has prevailed since Tuesday about what legal requirements for political expression remain in place since the emergency laws ended.

Arce, speaking to a crowd of about 15,000 Sandinista soldiers and followers in Managua, called the opposition "parrots" of Reagan administration policy, but warned the Sandinistas not to "respond to provocation" in the days before an upcoming U.S. congressional vote on contra aid.

If new military aid to the contras is passed, Arce warned, restrictions will be reimposed quickly on the opposition.

"We will not stand by and be attacked from outside with scorpions in our shirts. If the war continues, the scorpions will go back to their holes or we will crush them," he said.

A Sandinista crowd also staged a threatening demonstration at the headquarters of the Social Christian Party last night, party leader Jarquin said at a press conference this morning before he was hurt. Some party members were injured in fist fights, he said. Some Sandinistas were carrying rifles, he charged, but no shots were reported.

"We don't see any change. If there had been a big change since the state of emergency was lifted, this wouldn't have happened," said Violeta Rugama, a leader of the January 22 Movement, the prisoners' relatives group.

The sudden end to the emergency restrictions, however, is viewed as a major concession by government officials and some human rights groups that have monitored Nicaragua for several years.

"This was a very important move," said Aryeh Neier, vice chairman of the independent human rights group Americas Watch, in a telephone interview from New York. "Unfortunately in almost every country where there is a political relaxation, it is accompanied by some repressive nasty business. The government wants to signal the opposition it shouldn't go too far."

The end to the emergency, announced by President Daniel Ortega during a Central American summit last week, has pressed the government to make major adjustments to the new legal status of hundreds of political prisoners, as well as opposition activists who want to publish their views and demonstrate in support of their cause, government officials said. The state of emergency had suspended many constitutional guarantees that have now been restored.

According to official figures, 716 Nicaraguans were in custody awaiting trial in the Popular Anti-Somocista Tribunals, special courts for suspected contra collaborators that were also abolished Tuesday.