Nigerian police were holding two security guards yesterday in connection with an explosion that flattened a bank in Lagos, the commercial capital, killing at least 46 people.

Nigerian police were holding two security guards yesterday in connection with an explosion that flattened a bank in Lagos, the commercial capital, killing at least 46 people.

The two were employees of a security company that guarded the bank. Six others, the Prudent Bank's manager and five staff members, who were arrested on Wednesday for questioning were released yesterday.

After initially saying the explosion was an accident, the authorities reclassified the disaster as a bombing on Wednesday after finding explosives, including some not detonated, at the scene. "It was a series of explosions which brought down these buildings," Henry Iduode, of the police bomb squad, told the Lagos state governor, Bola Tinubu. as they visited the site.

Mr Iduode said he believed the explosives were of a type not manufactured in Nigeria.

Some of the material discovered so far included commercial explosives typically used in blasting quarries, a police spokesman said yesterday. Tests were continuing on other fragments.

The explosion on Sunday in a crowded residential and business district in the heart of Lagos destroyed buildings that housed a bank and dozens of apartments. By yesterday 36 bodies had been recovered from the rubble but more were believed to have died. Hospital workers say at least 10 people died of injuries at hospitals, taking the confirmed toll to 46.

The explosion scattered cash from the bank's deposits, and a number of young men were arrested for stealing the strewn money soon afterwards.

Authorities were considering a number of motives for the blast, including whether the explosion was part of a plot to rob the bank. (AP)