EAST BERLIN (AP) _ The Communist Party on Wednesday offered to hold talks with rival political groups on free elections and other reforms demanded during weeks of anti- government protests. Opposition leaders agreed.

Also Wednesday, a member of the ruling Politburo said the Communists' guarantee of a leading role in government affairs is unfair and should be abolished.

The ''dogmatic, distorted model of the political system should be changed in theory as well as practice,'' Poliburo member Wolfgang Herger said at a public lecture. His comments were the strongest indication to date that the Communists acknowledge the inequity of a constitutional mandate to rule.

At the same time, Communist Party leader Egon Krenz said the Communists won't be pushed around by the opposition and he has no intention of stepping down, the official ADN news agency reported.

In a Thanksgiving-eve speech, President Bush called recent changes in East Germany and other Soviet bloc countries ''a joyful end to one of history's saddest chapters.'' He spoke of East Germany's opening of the Berlin Wall but did not address the issue of possible German reunification.

The offer of talks from the ruling Politburo was vague about who could take part and did not set a date for negotiations.

Elke Guenther of New Forum, the biggest opposition group, said in response: ''We have wanted to talk to the Communist party for years. And there certainly are enough things to talk about.''

Lutheran Bishop Gottfried Forck said he expected the pro-reform group Democracy Now to organize opposition involvement. Rainer Eppelmann, of the Democratic Awakening group, said his group had not received an invitation to take part.

Talks between Communists and the opposition in Poland led this year to formation of a government there not led by Communists - the first in the East bloc.

Krenz, who serves as both party leader and head of state, told workers at a factory on the outskirts of East Berlin the party will keep its grip on the nation's factories - a traditional source of local control - and won't let itself be pushed ''up against the wall'' by the opposition.

''I didn't take over to push for change just for four weeks,'' ADN quoted Krenz as saying.

Krenz replaced his mentor, Erich Honecker, on Oct. 18, after the worst unrest in the nation's 40-year history and the exodus of tens of thousands of East Germans dissatisfied with years of stringent rule.

The government Wednesday ordered a ban on taking antiques or consumer goods out of the country, ADN said. No details were given, but the order appeared to be the first step toward halting the drain on the economy caused by East Germans taking heirlooms and state-subsidized goods to the West to sell for hard currency.

The offer to meet with the opposition was one of the Communists' most significant concessions in the current unrest, which began in September and has grown to include protests by hundreds of thousands of people across the country.

More than 100,000 East Germans left the country this month alone, testifying to continued dissatisfaction despite the opening of the Berlin Wall and lifting of travel restrictions.

Krenz's long partnership with Honecker and other Communists now suspected of having lined their pockets at public expense has tainted the new leadership and damaged the party chief's credibility.

Before the Politburo offer, Manfred Gerlach of the Liberal Democratic Party, long aligned with the Communists, said fledgling opposition groups such as New Forum deserve recognition and a greater voice in making decisions.

Ms. Guenther and other opposition leaders, however, were suspicious of his motives, having long suspected the Liberal Democrats of trying to establish themselves as the main opposition force.

''We are profoundly skeptical of the changes claimed by the established parties,'' Ms. Guenther said. ''Manfred Gerlach has long been a functionary within the government that has been discredited.''

Hans-Dieter Raspe, Gerlach's deputy, told ADN the Liberal Democrats aspire to the presidency in the first free elections, which some expect as soon as next spring.

Gerlach, at his first open news conference, said opposition groups should be allowed to compete with the Communists.

''This should be done both for the benefit of political pluralism and also to get as wide a range of participation as possible in deciding a future course,'' Gerlach said.

He pressed the Communists to relinquish their constitutional mandate for a ''leading role'' in the government, blaming their 40-year monopoly for economic decline and loss of public trust.

The Communists meet in a special party congress Dec. 15-17, and Krenz may be challenged if his popularity does not improve.

''I am concerned about proposals to have the delegates directly elect the general secretary,'' Krenz said Wednesday, indicating opposition to congress procedures that could bring in party members whose backing is uncertain.

Under the current procedures, delegates are elected by local party organizations, and the delegates vote in a new 163-member Central Committee. The Central Committee in turn chooses a party leader.

Under pressure to earn their posts in competitive elections, top-ranking Communists have reportedly splintered into groups that advocate differing paces of democratic change.

Some have also begun shunning privileges they've enjoyed for years, such as exclusive villas, as opposition demands for criminal investigations of former leaders are heeded.

The West German newspaper Bild reported Wednesday that Honecker's former deputy, ousted Politburo member Guenter Mittag, was interrogated for 14 hours last week about reports he stashed hundreds of millions of marks in Swiss banks.