DHAKA: Bangladesh's Islamist-backed main opposition on Sunday swept mayoral elections in four cities in a major setback for the ruling party ahead of general polls.

The centre-right Bangladesh Nationalist Party (BNP) won by big margins in the major cities of Khulna, Sylhet, Rajshahi and Barisal, Election Commission spokesman S.M. Asaduzzaman told AFP.

In the third largest city of Khulna, home to about one million people, BNP candidate Moniruzzaman Moni beat the incumbent Abdul Khaleque by a margin of 60,671 votes.

Analysts said the results reflected a nationwide erosion of support for the ruling Awami League party six months ahead of general elections, while the growing influence of Islamists who backed the BNP after their traditional parties did not contest contributed to the huge margins of victory.

“In mayoral elections local issues play important role but the results are a verdict against the government's poor performance,” said Ataur Rahman, a former professor of political science at the National University of Singapore.

“Many people believe this government is anti-Islamic and they did not like the way government aggressively cracked down on the Islamists in recent months,” Rahman added.

Leading Islamists including the entire leadership of Jamaat-i-Islami have been tried by the country's much criticised war crime court that is probing the atrocities committed during Bangladesh's 1971 war of independence.

Four Islamist leaders have already been sentenced to death since January by the court but the verdicts triggered protests which killed 150 political activists, mostly Islamists, in some of the worst political violence in the country's history.

Prime Minister Sheikh Hasina's centre-left Awami League party won the December 2008 polls by a landslide but her tenure has been hit by series of high profile graft scandals.

The BNP, led by former prime minister Khaleda Zia, has won power three times.