Malawi police fired tear gas at thousands of demonstrators who took to the streets of the capital Lilongwe on Tuesday, in the latest wave of protests over the disputed May presidential election.For five months the southeastern African country has been shaken by demonstrations demanding the resignation of the electoral commission chairwoman Jane Ansah, who they accuse of rigging the vote in favour of President Peter Mutharika.The police were unprovoked when they fired tear gas at protesters gathering for the march, protest leader and reverend MacDonald Sembereka said."People were just assembling, dancing and singing when the police came and started firing tear gas at the marchers," he told AFP.One person was hospitalised with a suspected bullet injury, but hospital administrator Jonathan Ngoma refused to confirm if it was a bullet wound until after surgery.Police spokesman James Kadadzera did not comment.Following the clashes, the Malawi army came and offered security to demonstrators who then re-grouped and resumed marching to Capital Hill, the seat of the Malawi government.The organisers of the protest, the Human Rights Defenders Coalition (HRDC), accuse Ansah of mismanaging the election, which they claim was marred by gross irregularities.But the elections chief has refused to step down.Mutharika narrowly won his second term in the May vote.Opposition parties Malawi Congress Party and United Transformation Movement have petitioned the Constitutional Court to nullify the election results.Previous demonstrations since May have also been marred by skirmishes between police and protesters.Last week, Justin Phiri, a protester in the northern city of Karonga died in police custody after he was allegedly assaulted by soldiers and later arrested. Family lawyer Bracious Kondowe told AFP that preliminary results of the post-mortem showed "overwhelming evidence that the wounds were as a result of assault".Another protest organiser, HRDC's Happy Mhango, said it was a "sad day for democracy" that death was "the price he had to pay".Military spokesman Paul Chiphwanya said the army was officially unaware of the incident, having only "read about the story in the newspapers"."No one has contacted us regarding this story. People are saying he was assaulted by the army but we don't know how true that is," he said.