The finance ministry has asked three of its investigating arms to probe all exports to tax havens Bahamas and Cyprus, an official in the ministry told ET on the condition of anonymity.

The ministry is concerned about the sudden surge in exports to the tax havens and has asked the agencies to ascertain whether the exports are genuine, said the official, who declined to be identified given the sensitivity of the matter.

A communication asking for a co-ordinated probe was sent from the revenue department to the Central Board of Direct Taxes ( CBDT), the Directorate of Revenue Intelligence ( DRI) and the Enforcement Directorate ( ED).

In the last two years, exports to Bahamas, a so-called tax haven, from India have surged from $2.2 million in 2008-09 to $2.2 billion in 2010-11. The sudden increase in exports has raised suspicions that a chunk of the transactions could be fraudulent.

"The revenue department has asked the agencies to verify the transactions since it has come to light that in some cases, the export figures do not match the inward inport figures of the two tax havens," an official in one of the agencies told ET.

He declined to specify how many such transactions have come to light, stating that the investigations were sensitive and at a preliminary stage.

The agency has written to the concerned countries for more detailed information on its imports from India to as part of its investigations, he said.

Concerns have been raised within the government on whether these transactions are a way of bringing back black money into the country through export over-invoicing. This happens by billing the overseas buyer several times more than the actual worth of the goods. In many cases, the so-called overseas buyers are shell companies or do not exist.

The Bahamas is one of the jurisdictions to have signed a tax information exchange agreement with India. Some of the others include Bermuda, Isle of Man, British Virgin Islands and Cayman Islands. Countries signing such a pact are required to share information if the other country has reasonable ground to believe that there has been a tax offence.

For the last few months, analysts have questioned India's export numbers which have shown robust growth at a time the US and Europe - the two biggest markets - are facing slowdown. While some have attributed this to inept data handling, a recent report by Kotak Institutional Equities Research has harped on the possibility of black money inflow.

The report, authored by Sanjeev Prasad, Sunita Baldawa and Amit Kumar, draws no definitive conclusions, but said, "We can attribute some part of these gaps to data limitations but the large difference between official data and our observations begs a better and more sophisticated explanation."

It highlights how export data of major engineering companies, including automobiles and metals, does not match the steep increase in official export numbers.