A senior Polish official attempted today to dampen speculation of an imminent end to martial law or the release of Lech Walesa, leader of the Solidarity trade union federation.

Deputy Prime Minister Mieczyslaw Rakowski said at a press conference here that no date had been set for lifting martial law, which was declared Dec. 13. He said Polish authorities want to use the period to introduce economic reforms, including long-delayed price increases.

"It would be unrealistic to think that we could free interned Solidarity leaders soon," he said. "This would mean a restoration of the situation prior to Dec. 13."

Yesterday Poland's ambassador to Britain, Stefan Staniszewski, was quoted as saying that a decision had already been made to release Walesa, who is being held in Warsaw. But Deputy Foreign Minister Jozef Wiejacz said he believed that the ambassador had been quoted out of context.

"He is always an optimist," he said.

Rakowski, asked whether Walesa would be free within three weeks, replied: "I don't know." He also said he had been misquoted by a Western news agency in predicting that martial law would end soon.

In an interview published Monday by the West German magazine Stern, Rakowski was quoted as saying the government saw no point in negotiating with Walesa because he carried little weight without his advisers.

"For me, there is no doubt that Walesa has little significance without his advisers," Rakowski said. "He lacks insight, he easily loses contact with reality. He is a great speaker to the people but it is hard to get a constructive answer to a large political problem."

Rakowski was also quoted by Stern as indicating that the regime feared a quick return of chaos if martial law were lifted too soon. "If we really want reform and the economic stabilization that would make these reforms possible, then we cannot lift these measures taken with a heavy heart, and create a situation in which the whole chaos would return within a month at the latest," he said.

Rakowski's remarks today, along with the private comments of other Polish officials, reflected uncertainty over how the country would be run once martial law is lifted. He said that talks are going on over the future of the trade unions but refused to predict whether Solidarity would be merged with the official Communist-dominated trade unions.

Western analysts here predict that, while specific martial law restrictions may be lifted gradually, the main controls over the population will remain in force for some months. Poland's military rulers are believed to be very apprehensive over possible public anger over price increases of up to 400 percent planned for many consumer goods and foods.

Addressing his first press conference since the military crackdown, Rakowski said the Polish leadership regarded martial law as the only alternative to civil war.

"We had to do something to stop a train full of passengers from rushing over a precipice," he said.

Rakowski, who is believed to be one of the closest advisers to Gen. Wojciech Jaruzelski, the prime minister and party leader, denounced Western trade sanctions against Poland and the Soviet Union. He said they might make it more difficult to relax strict military rule.

Rakowski expressed satisfaction with relations with the Roman Catholic Church. Church officials have been acting as mediators between the government and Solidarity and today a joint church-government commission held its first session since the imposition of martial law.

Asked about a planned return visit to Poland by Pope John Paul II in August, Rakowski said the matter had not yet been discussed but the pope remained welcome. Many Poles believe that it was the pope's visit here in 1979 that started the chain of events that gave birth to Solidarity.

Asked about the recent decision of his son, Artur, 23, who lives in West Germany, to seek political asylum in the West, Rakowski described it as a personal blow. He said it was "a dramatic example of a gap between a generation which fought for a new Poland and their children." The gap had been widened, he said, because many young people did not believe they had a future in the country.

Criticizing the journalist who raised the question, Rakowski said: "Somebody is using this fact for political ends. One has to respect a father's drama in this matter."

Associated Press reported the following:

The Polish news agency said in a commentary that the government must raise prices for food, clothing and other necessities to keep the economy from total collapse.

In what appeared to be an attempt to lay the groundwork for new price increases, the government news agency PAP said prices must be increased if food, clothing and other products are to remain available.