Police threatened Monday to deal "ruthlessly" with anyone who joins a strike to protest an internationally condemned government demolition campaign that has left at least 200,000 homeless in the middle of winter. A previously unknown group calling itself the Broad Alliance urged people to stay away from work Thursday and Friday to protest police demolition of shacks around the country and the arrest of more than 30,000 street traders.Police Assistant Commissioner Wayne Bvudzijena promised to deal "ruthlessly" with those who stay away from work. Under Zimbabwe's law, anyone convicted of attempting to "coerce" President Robert Mugabe's government risks a 20-year jail term. Opposition parties are "trying to take advantage of the clean-up exercise to make political capital," Bvudzijena said, adding that government opponents had hired youths to build highway barricades. The government has said the campaign, which began May 19, is aimed at cleaning up cities and crushing the black market for scarce staple goods like cornmeal, sugar and gasoline.