Lech Walesa, leader of Poland's outlawed Solidarity trade union, today released the text of a letter addressed to Poland's military ruler, Gen. Wojciech Jaruzelski, outlining Walesa's conditions for national reconciliation.

In the letter, dated Dec. 4, Walesa called for a general amnesty for Solidarity activists convicted under martial law, the reinstatement of workers dismissed from their jobs and the restoration of independent trade unions. He said he timed the letter to coincide with expected government moves to lift or suspend martial law next week.

Walesa gave the text of the letter to a representative of ABC News in Gdansk after what he called a misleading and incorrect version was leaked to some Western newspapers, apparently by government sources, earlier this week. Walesa could not be reached for comment, but the authenticity of the new text was confirmed by his associates in Warsaw.

Walesa, who was freed Nov. 13 after 11 months in detention, told ABC that he also had sent a statement to the official Polish news agency PAP denouncing all other versions of his letter as "fakes." One such version, published last week in a British newspaper, suggested that Walesa had distanced himself from the Solidarity underground and had come close to joining government efforts in putting an end to illegal union activities.

The full text of his letter does not refer to the Solidarity underground. It contains Walesa's own carefully worded assessment of the steps he believes the Communist authorities need to take if they are to win popular support.

"The deep and prolonged crisis can only be overcome by the efforts of all of society," Walesa's letter to Jaruzelski says. "This is also necessary in order to get foreign aid that is being withheld at present for political reasons."

"The rekindling of social initiative and strengthening Poland's position in the world is only possible through rebuilding mutual trust between society and the government."

Release of the letter marks Walesa's first significant public statement since the day after his release, when he gave interviews to foreign correspondents. At that time, he said he wanted a month's rest to inform himself about the situation in Poland before deciding on his next move.

In his letter, Walesa adds that mutual trust between society and the government could be rebuilt only on the basis of the agreement signed in Gdansk in August 1980 allowing the formation of independent unions in Poland. It was this agreement that put an end to a strike by shipyard workers led by Walesa. The strike precipitated the birth of Solidarity.

"Without the acceptance of the government's position by the working class, we will not get far," Walesa wrote. "These steps would open the way to a real social agreement. I am ready to take part in work leading to this objective. None of us would be doing the other a favor, and noneof us has to ask for agreement on our knees, since agreement is a necessity if you care about the good of the country."

Government spokesmen have insisted that Walesa, as "the ex-chairman of the ex-Solidarity," is now merely a private citizen. They have also ruled out any meeting between Walesa and Jaruzelski in the near future.

It is significant, however, that there is no mention of Solidarity in Walesa's latest statement. On the central question of the future of trade unions, he says only that the government should concede the principle of pluralism that was recognized in the Gdansk agreement.

Under a new law on trade unions passed by the Sejm, the national legislature, in October, only one union can be formed in each factory until the end of 1984. So far, officially inspired attempts to set up new trade unions have been boycotted by a vast majority of Solidarity's former 9.5 million members.

The Sejm has been called into session Monday, the first anniversary of martial law, to discuss whether it should be ended. West European governments were informed by Polish officials earlier this month that martial law would almost certainly be lifted altogether--but since then stories have circulated here that it may only be suspended.

In a statement today, Deputy Defense Minister Jozef Baryla said the government would have to be equipped with "special powers" over a transitional period to ensure that Solidarity did not resume its activities. The Army newspaper, Zolnierz Wolnosci, also has suggested that lifting martial law completely could be premature.

Part of the reason for the apparent change in plans could be the lukewarm Western response to suggestions that economic sanctions against Poland should also be swiftly ended. In a speech yesterday, President Reagan said sanctions would only be lifted if, in addition to the ending of martial law, "all political prisoners" were released and negotiations resumed between the government, the Roman Catholic Church and the trade unions.

According to figures released by the Interior Ministry this week, 3,616 people have been arrested for "political" offenses during the past year. Out of the more than 10,000 people interned for all offenses since the imposition of martial law, 317 were still being held as of Dec. 8.

The internees, mainly senior Solidarity officials and advisers, would presumably be released if martial law is lifted -- but people convicted or charged with illegal trade union activity would remain in detention.