David Cameron has promised to “respond to any request for information” on corruption allegations over India’s procurement of helicopters from the Anglo-Italian company AgustaWestland.
India has suspended payments under the terms of the £480m contract, following arrests at AgustaWestland and its parent firm Finmeccanica.
Mr Cameron, visiting India, stressed Finmeccanica was an “Italian company”.
The company said it had acted correctly in reaching the deal.
Mr Cameron held talks with Indian Prime Minister Manmohan Singh in Delhi on the second day of his three-day trade visit.
Afterwards Mr Singh said he had raised “serious concerns” about the AgustaWestland deal.
AgustaWestland signed a contract to supply 12 AW101 helicopters to the Indian air force in 2010, since when there have been allegations of bribery, which are being investigated by the Italian authorities.
Finmeccanica’s chairman and chief executive Giuseppe Orsi and AgustaWestland chief executive Bruno Spagnolini were arrested last week on corruption and tax fraud charges.
At a press conference after his meeting with Mr Cameron, Mr Singh said he had “conveyed to the prime minister our very serious concerns regarding allegations about unethical means used in securing the 2010 contract for AgustaWestland helicopters.
“I told him that we have sought an explanation from the company by 22 February to examine if the contractual conditions on unethical practices and the integrity pact have been violated.
“I have sought full assistance from the UK in this case. Prime Minister David Cameron has assured me of the co-operation of his government in the investigation.”
Mr 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.”
He added: “In Britain, we have introduced anti-bribery legislation that is probably the strongest anywhere in the world and we will root out any problems of bribery and corruption wherever and whenever they appear.”
Mr Cameron told the BBC he shared India’s “concern”, saying: “I will work closely with the Indians to make sure that they get to the bottom of what’s happened here.
“There’s no embarrassment about this. This [ensuring clarity] is exactly what our partnership should be delivering.”
AgustaWestland employs more than 3,000 people in Yeovil, Somerset.
During their talks Mr Cameron and Mr Singh also agreed more co-operation between Britain and India in combating cyber attacks, including police training exchanges and research into online security.
Mr Cameron said the countries were “on track” to double overall trade to £23bn by 2015.
The UK prime minister, whose delegation includes representatives from BAE Systems, Rolls-Royce, London Underground and the English Premier League, will also meet Indian President Pranab Mukherjee during his trip.