Solidarity union founder Lech Walesa called for May Day protests to demand the release of political prisoners in Poland. "We have not learned how to defend our (opposition) leaders. They are being spat upon, and we have to defend them," Walesa told about 500 cheering supporters in the northern seaport of Gdansk. Sources in the outlawed Solidarity trade union estimate there are 107 political prisoners in Polish jails. Last week, three Solidarity activists were charged with trying to incite unrest by planning a 15-minute general strike to protest government-ordered price increases.