David Cameron's efforts to build a "special partnership" with India have been overshadowed by questions over alleged corruption in a UK-based company's contract to supply helicopters to the country's airforce.
The allegations against AgustaWestland have made front-page news in Indian newspapers during Mr Cameron's three-day visit, and Indian prime minister Manmohan Singh used a joint press conference to raise "very serious concerns" about possible ethical breaches.
Mr Singh asked for assistance from the UK authorities as Indian investigators look into the allegations. Mr Cameron - who praised Westland's operations in Yeovil on Monday and insisted the allegations were a matter for Italian and Indian authorities, and not the UK - assured him that Britain will respond to any request for information.
India has suspended payments under the £480 million contract following Italy's arrest on corruption and tax fraud charges of Giuseppe Orsi, the chairman and chief executive of AgustaWestland's Italian parent-company Finmeccanica, as well as AgustaWestland chief executive Bruno Spagnolini.
At a joint press conference following talks in Hyderabad House, New Delhi, 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".
The company had been given until February 22 to explain whether "contractual conditions on unethical practices... have been violated", said the Indian PM. And he added: "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: "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."
Britain has some of the strongest anti-bribery legislation in the world and will "root out any problems of bribery and corruption wherever and whenever they appear", Mr Cameron promised.
He later told the BBC that he shared Mr Singh's concerns, saying: "The defence trade, the defence industry, is an important industry for Britain and I want that to be a clean industry and a clean trade.... Be in no doubt we absolutely condemn these sorts of practices."
Finmeccanica said it had "acted correctly throughout the 40 years it has operated in India".