WARSAW, JUNE 24 -- Sixty-three of Lech Walesa's senior advisers and longtime allies in the Solidarity labor movement broke ranks with him today over his criticism of Poland's Solidarity-led government and demanded dissolution of the national Citizens' Committee, the movement's political wing.

The break came in a meeting here of the 200-member Citizens' Committee at which the 63 activists declared in an open letter that the body should be disbanded because Walesa had undermined its unity of purpose and that there was therefore no further reason for its existence.

The letter was read out at the end of a daylong meeting of the committee, the mechanism through which Walesa and his new detractors had worked side by side to overcome four decades of Communist rule, and it appeared to mark the end of an era of opposition unity. The 63 dissidents said they want the committee, recently packed with new members beholden to Walesa, to abolish itself. They called for a new body to firmly support the Solidarity government as it seeks to reshape Polish society in what they consider the spirit of Solidarity's founding ideals.

The committee membership, including the 63, agreed at Walesa's behest to postpone considering action on the letter for a month to allow emotions to cool. "Let's think it over," said Solidarity leader Walesa, who chaired the meeting. "Maybe there are solutions for our further joint path."

The signers of the letter, who agreed to remain on the committee in the meantime, include such major Solidarity figures as Zbigniew Bujak, Adam Michnik, Bronislaw Geremek, Jacek Kuron, Henryk Wujec and Wladyslaw Frasyniuk, men who were once Walesa's closest allies in the struggle to force the long-ruling Communists to share power with the opposition.

But now they differ with Walesa over his criticism of the government of Prime Minister Tadeusz Mazowiecki -- himself a longtime Solidarity activist -- and what Walesa considers the slow pace of economic reform. The former allies also disagree with Walesa's drive to become president of Poland and his opening up of the Citizens' Committee to members of political groups outside the Solidarity movement.

Mazowiecki stayed away from the meeting, but in a speech in Szczecin he appealed for national unity until the country completes painful economic reforms.

"The greatness of the tasks we are facing today requires an emphasis on going through the most difficult time together. . . . It requires a broad democratic consensus and avoiding a demagogical bidding war" of political promises, Mazowiecki said.

The emotional debate among Citizens' Committee members today was tinged with sadness and anger. "I have a feeling that I have lost something," said Geremek, leader of the Solidarity caucus in parliament. "In our movement, there used to be no leader, there were no servants. There were citizens. There were friends. . . . What happened?" he asked, addressing Walesa.

Michnik is editor of Poland's most widely read daily newspaper, Gazeta Wyborcza, which was founded in support of Solidarity candidates in last year's free elections and whose use of the Solidarity logo Walesa now disputes. Michnik told Walesa today that he had no right to say who could use the name of Solidarity and declared: "Nobody can take away our struggle, not even you, Lech."

Opening the meeting, Walesa pleaded for the two sides to work out problems together through candid discussions. But at the same time, he strengthened his hold on the committee by winning the resignation of Wujec, the group's longtime secretary, who had sided with the opposing faction.

Walesa said his recent criticism of the government, including a vow to create a "war at the top," had been intended to help the prime minister by conveying the frustrations of workers and farmers eager for faster improvements in their lives.

Mazowiecki's government was defended by veteran independent newspaper editor Jerzy Turowicz, who said the government's economic reform program "is the only possible road now, although it's difficult."

Walesa also has criticized the government for moving too slowly to oust former Communists from positions of authority, and he says he fears his former allies in Solidarity might create a new power monopoly in the government and parliament.

Walesa aides recently formed a political group, the Center Alliance, to promote his election to the presidency of Poland, now held by former Communist leader Wojciech Jaruzelski.

Walesa critics charge that he is becoming a danger to democracy because he stirs emotions against the government. They predict that as president of Poland he would rule by decree, undermining Poland's democratically elected government.