A candidate backed by Bangladesh's main opposition party won a crucial mayoral election, defeating his pro-government opponent by a large margin, officials said Friday, according to dpa. The opposition Bangladesh Nationalist Party-backed contender M Manzur Ahmed won Thursday's poll, bagging 479,145 votes to run Chittagong City Corporation for the next five years, election official Jesmin Tuli said. She said Manzur's nearest rival, ABM Mohiuddin Chowdhury, a candidate of the ruling Awami League party and a three-time mayor of the port city, polled 383,617 votes. This is the first major election defeat suffered by a ruling party candidate since the Awami League-led coalition took office with an overwhelming parliamentary majority in the December 2008 general elections. Apart from a few isolated incidents, Thursday's voting was generally peaceful amid tight security. The Election Commission put the turnout at 54.5 per cent. Voters also elected city councillors for 41 wards.