Zimbabwe's president and prime minister have condemned disturbances at a meeting to discuss a new constitution, and issued a call for unity. President Robert Mugabe told a news conference that the government would "not brook any further nonsense". The comments came after the meeting was abandoned when fights broke out between his supporters and those of his former rival Prime Minister Morgan Tsvangirai. Mr Mugabe's supporters disrupted the opening speech by dancing and singing. At a joint press conference with Mr Tsvangirai, Mr Mugabe said it was necessary to complete the update of the charter. "These things we'll continue to rectify and improve as we move forward," he said. "Rome was not built in one day." Mr Tsvangirai said the disturbances did not benefit anyone. "Whether as a political party or as a nation, we are only hurting our efforts," he said. On Monday, water bottles were thrown and scuffles broke out between politicians from both parties in Zimbabwe's power-sharing government. Some delegates walked out in protest and riot police were brought in to clear the venue. Mr Mugabe's Zanu-PF party wants the new constitution to be based on a draft drawn up last year, but critics say it gives the president too much power. Source: BBc