Maputo - The spokesperson for Mozambique's main opposition party has been arrested after leading a demonstration protesting against the result of last October's election, police said on Tuesday.The ruling Frelimo party and its candidate Filipe Nyusi won the presidential and legislative elections, a result certified last week by the country's constitutional court.The Renamo opposition party and its candidate, former civil war rebel leader Afonso Dhlakama, have alleged widespread fraud and irregularities, including ballot stuffing.The party's spokesman Antonio Muchanga has since called for nationwide demonstrations and on Saturday led a march in the capital Maputo to protest the result, which police said was illegal because permission had not been obtained in advance."The spokesperson for Renamo was arrested today. He led last Saturday an illegal demonstration in Maputo. In addition he has delivered speeches that incite violence," police spokesman Orlando Mudumane told a news briefing.Tensions are running high in Mozambique. In the run-up to the election, Renamo partisans clashed sporadically with troops and police. The Renamo leader only emerged from a bush hideout in September to reaffirm a 1992 peace pact which ended a 17-year civil war.Mozambique is hoping revenue from its large natural gas deposits and its fledgling coal mining industry will help it emerge from years of poverty and aid dependence.