Several hundred Solidarity supporters demonstrated peacefully outside the Lenin Shipyard in Gdansk today on the eve of a threatened week-long work slowdown marking the third anniversary of the agreements that led to formation of the now-banned union.

Solidarity founder Lech Walesa, who said a week ago that he would be at today's gathering, canceled his appearance at the last minute, telling reporters his presence at a demonstration now could lead to his detention and endanger other Solidarity activists.

"Everything was called off," Walesa said after leaving his job at the shipyard and driving to the residence of his close friend, the Rev. Henryk Jankowski. "Otherwise, I knew I would have found myself in jail for a month."

Walesa said his action would not affect the work slowdown scheduled to begin Tuesday. It was called by a clandestine shipyard cell that had demanded that the government open talks with Walesa by today.

As shifts changed early this afternoon, a crowd of several hundred gathered outside the sprawling shipyard, the scene of strikes in 1980. Waiting expectantly for Walesa, they sang the national anthem and held up the V-for-victory sign that has become a Solidarity symbol.

Many laid flowers near the main gate at the soaring steel monument that is topped by three crosses in memory of the scores of shipyard workers slain here in a clash with police in 1970.

Few police were in sight today, and except for the brief detention of an ABC television crew, authorities made little effort to interfere, despite a regional order issued after minor disturbances here last week for misdemeanor courts to use accelerated procedures to deal with demonstrators.

Reflecting government nervousness about the week leading up to the main Solidarity anniversary date, Aug. 31, Gdansk authorities issued a tough warning over the weekend to potential protesters, asserting that the "forces of law and order" would "ensure calm and uninterrupted work in the province."

The Communist Party daily Trybuna Ludu appeared particularly concerned about the damage a national work slowdown would do to Poland's already crippled economy, suggesting that workers would be shooting themselves in the foot if they joined in the threatened protest action.

"Refraining from work now when we are slowly starting to recover from economic collapse," the paper said, "would mean wrecking hopes for improvement in our social conditions for a long and distant period of time."

But authorities have refused to do the one thing that would certainly relieve the tension: hold talks with Walesa. Instead, they have fired a new barrage of mocking insults at him, portraying him as a tool of American anti-Polish interests, as an egotist and as a self-aggrandizing opportunist.

The attack seems to be motivated by official frustration not only at Walesa's continued national popularity and political activism but also at his recent contacts with visiting foreign dignitaries--among them U.S. Sen. Christopher J. Dodd (D-Conn.), who was told by Walesa that the United States should not lift economic sanctions against Poland despite the formal ending of martial law last month.

In a bitter reference to Walesa, Polish state radio told its listeners over the weekend: "When you line up for a fish or a chicken, it is worth remembering that the millionaire from Gdansk wants this line to be still longer." The radio said Walesa has amassed more than a million dollars in gifts and awards, an allegation Walesa has dismissed as nonsense.