The UPA is in damage control mode over allegations that Indian officials took millions of dollars as bribes to help American companies secure government contracts.

Five ministries are investigating specific charges of bribery against their officials, after the Indian ambassador to the US wrote a letter to the Centre.

The Agriculture Ministry has asked the CBI to investigate allegations that US-based Dow Chemicals paid $ 200,000 to register 3 of their pesticides - which are banned in the US.

"We are probing the matter," said Finance Minister Pranab Mukherjee.

NDTV has learnt that the Prime Minister's office referred the bribery scandal for investigation on June 1 this year. In fact on August 19, the PMO asked for an Action Taken Report from the Department of Personnel and Training - which is monitoring the investigations.

In government circles, the allegations first surfaced in May, when India's ambassador to the US Meera Shankar wrote to the PMO giving details of US companies that allegedly paid millions of dollars.

The Maharashtra State Electricity Board was allegedly paid 1 million dollars by Mario Convino of Control Companies Inc. Indian Navy and Defence Ministry officials allegedly received bribes to the tune of 7.5 million dollars by York International Corp. Bribes were also allegedly paid to officials of the Department of Revenue to get customs clearances.

Indian Railways were allegedly paid bribes by Westinghouse Air Brake technology. "We will take action if some wrong has taken place," said Railway Minister Mamata Banerjee.

The opposition has accused the government of shielding the guilty, by not making the letter public. The CPM has demanded that all the US companies mentioned in Meera Shankar's letter be blacklisted. Clearly, with both the right and the Left speaking in one voice, the government's under pressure to fast-track the investigations.