Bus drivers led by state-sanctioned communist unions went on strike Friday to press wage demands as Solidarity leader Lech Walesa warned that simmering labor unrest threatened progress in his banned union's talks with the government.

The official news agency PAP said buses in the southern city of Piotrkow Trybunalski and neighboring towns in the same province did not leave their depots Friday, leaving at least 173,000 people with no way to get to work."It is a strike led by the official unions, members of the Federation OPZZ," a spokesman for the state-sanctioned labor group said in Warsaw. The drivers are demanding wage increases of $46 a month, PAP said. The average monthly wage in Poland is $124.