Solidarity leader Lech Walesa on Friday pleaded with holdout strikers to return to work at a mine where a wave of labor unrest began 18 days ago. Poland's prime minister made a similar mission to a nearby mine.

In Szczecin, 1,800 dockworkers and 600 bus depot workers offered to end their strike as soon as job security is guaranteed for the bus workers, said Interfactory Strike Committee member Artur Balasz. He said strikers idled since Aug. 17 were awaiting management's response.The end of the Szczecin strikes would leave the July Manifesto mine in Jastrzebie in southwestern Poland the only facility in the country still on strike. Workers there left their jobs Aug. 16.

Walesa urged strikers at July Manifesto to give up their strike in exchange for a government promise to begin national talks on legalizing the trade union Solidarity.

Walesa's talks with strikers at the mine continued past midnight. A Polish journalist who asked not to be identified said there was progress in the negotiations and added, "Everybody is waiting for a happy finale."

Prime Minister Zbigniew Messner turned up unannounced at the neighboring Borynia coal mine to discuss workers' concerns, Polish media said. The mine, within sight of July Manifesto, went on strike from Aug. 20-24 and labor tensions have persisted there.

Walesa began talking to strikers at the July Manifesto mine immediately after arriving in the morning with an aide and his parish priest, Rev. Henryk Jankowski, said management spokesman Antoni Pilny. Pilny later said the strikers were resisting going back to work until local issues were settled.