Plainclothes police surprised sleeping workers with percussion grenades Thursday in a pre-dawn raid that ended a 10-day strike at the huge Nowa Huta steel mill outside Krakow, official and church sources said.

At the Gdansk shipyard, site of another major workers' strike, communist authorities ordered a lockout Thursday, and police in full riot gear ringed the yard.In Warsaw, Solidarity's national spokesman was reported arrested, and the government accused strike leaders of trying to provoke crisis.

The government reported new work stoppages Thursday among transit workers in the northwestern port of Szczecin and the nearby municipality of Police. Students also began a strike at Warsaw University.

"The moment of the solution similar to that at Nowa Huta is approaching," Solidarity leader Lech Walesa said in a taped interview smuggled out of the Lenin shipyard in Gdansk. In a tense-sounding voice, he vowed to be "the last to leave."

In a communique, the shipyard strike committee had called on workers to come to the yard: "We continue the strike with a feeling of responsiblity for the shipyard and for the country."

Hundreds of workers inside loudly chanted "Solidarity, Solidarity," and sang religous songs and the national anthem.