Police clashed with Basque separatists during a protest march in the northern Spanish city of San Sebastian on Sunday, media reports said, according to DPA. Police fired rubber bullets after some of the marchers pelted the officers with stones, the reports said. Two people were arrested. The clashes erupted after police tried to stop the march, which was called by an organization seeking an amnesty for jailed members of the Basque separatist movement ETA. Authorities had earlier banned the march. On Thursday, Spain's top court ruled that a plan by the Basque regional government to stage a referendum-like vote on the self- determination for the northern region was unconstitutional. The Basque parliament had approved holding the vote on October 25, but the Spanish government and opposition conservatives lodged a complaint with the Constitutional Court.