Mohammad Refayet Ullah, the mayor of Savar, was arrested in the capital late Wednesday exactly three months after the Rana Plaza building collapsed in one of the world's worst industrial disasters.

Local police chief Mostofa Kamal said Ullah, who was suspended as mayor in the wake of the tragedy, had been wanted for questioning over the nine-storey structure, housing garment factories, that flouted building codes.

"CID (Criminal Investigation Department) officers who are probing the case arrested him from Dhaka," Kamal told.

Ullah, an opposition official who for the last 14 years has been the mayor of the satellite town outside the capital, home to scores of garment factories, is the highest official to be arrested over the disaster.

Officials have said his office allowed three extra floors to be added to the building, which only originally had permission for six. His office then failed to take action when cracks appeared in the overburdened structure, one day before the tragedy.

A government team investigating the disaster, which has inspected the site, has said contractors had used shoddy construction materials to build the floors.

Heavy generators had been placed on the upper floors, so that factories could keep churning out clothes for Western retailers during power cuts, in violation of the country's construction laws.

More than a dozen people, including the owner of the building and the owners of four factories housed there, have been arrested over the disaster, which highlighted appalling safety conditions in Bangladesh's 4,500 garment factories.

Although the investigation team has suggested that the owners and those who abetted the building construction be prosecuted for culpable homicide, police have not yet pressed final charges against them.

The April 24 disaster has prompted the United States to suspend trade privileges to impoverished Bangladesh. The tragedy also drew a consumer backlash against Western retailers who buy up to 80 percent of Bangladesh's $21.5 billion annual apparel shipments.