DHAKA - AN employee of Bangladesh's biggest state-owned gas company who earned a mere US$100 (S$141) a month managed to pocket a colossal US$145 million (S$205 million) in bribes over 12 years, an official said.

'It is a theft of unimaginable scale,' said the head of the government's anti-corruption body, Colonel Hasan on Tuesday.

He identified the culprit as Abdul Kader Mollah, a former sales assistant with the Titas Gas Distribution Company who made illicit cash by undercharging thousands of factories before leaving his job in 1997.

'During his 12 year career his monthly salary was around US$100. But he became a multi-millionaire,' the official said, adding the 46-year-old gas worker was 'feared by everyone' and enjoyed union and political connections.

Mollah's fortune - now estimated by authorities at over US$300 million - was revealed after the military-backed government launched an investigation into the company last year as part of a nationwide anti-graft drive.

But Mollah - who is still under investigation and has not yet been arrested - hit back at the allegations by taking out a quarter-page advertisement on Tuesday in at least 11 top newspapers.

He insisted he was only worth US$66 million and also said he made the money through hard work at Titas, the country's largest state-owned gas distributor with an 80 per cent market share.

Last week, authorities said at least 80 per cent of Titas' 2,800 workers had made millions of dollars by under-charging in exchange for bribes, although 127 workers have so far agreed to return such money to the state.

Bangladesh's government, which came to power in January 2007 following months of political instability, has detained more than 150 politicians, including former ministers accused of accepting bribes for official duties.

In October it widened the drive to state-owned companies.

The country is considered one of the most corrupt nations in the world by Transparency International, which ranks graft worldwide every year. -- AFP