Cameron, leading a large British trade team on a three-day Indian visit, met Indian Prime Minister Manmohan Singh and other leaders Tuesday in New Delhi.
The visit came at a time when the Indian government is facing accusations of corruption from opposition parties in the procurement of 12 helicopters under a $745 million deal from the Anglo-Italian company AgustaWestland and its parent in Italy Finmeccanica.
In a statement after his meeting with Cameron, Singh said he informed Cameron of "our very serious concerns" regarding allegations about unethical means used in securing the 2010 contract for AgustaWestland helicopters.
"I have sought full assistance from the U.K. in this case. Prime Minister David Cameron has assured me of the cooperation of his government in the investigations," Singh said.
Italy is conducting its own investigation into the deal.
Cameron said: "In terms of AgustaWestland, we will respond to any request for information. I am glad that the Italian authorities are looking into this issue in detail, as Finmeccanica is an Italian company," the BBC reported.
On Monday in Mumbai, the first stop on his India visit, Cameron said India's "rise is going to be one of the great phenomena of this century," and that "Britain wants to be your partner of choice."
The countries want to more than double bilateral merchandise trade to $34 billion by 2015.
Singh, in his statement Tuesday, said Cameron's "strong personal commitment and leadership" had imparted a strong momentum to the strategic partnership between India and the United Kingdom.
Singh said he and Cameron in their talks stressed the need to take their bilateral relationship "to a new high level" and that he invited British investments in India, including participation in a possible industrial corridor in the Mumbai-Bangalore sector.
"We discussed prospects of enhanced cooperation in the development of the defense industrial base of India through greater emphasis on technology transfer, co-development and co-production," Singh said.