British Prime Minister David Cameron has met with his Indian counterpart Manmohan Singh, as part of a three-day visit aimed at doubling trade between the two nations to $36bn.
Tuesday's meeting took place amid a corruption row over a $750m defence deal in India involving AgustaWestland, a British-Italian helicopter maker.
India is considering cancelling the deal after Italian police arrested Giuseppe Orsi, the former head of the parent company Finmeccanica, for allegedly paying bribes to Indian politicians to win the contract.
Address the helicopter deal, Caneron said: "Let me make absolutely [clear] that in Britain we have introduced anti-bribery legislation that is probably the strongest anywhere in the world."
Singh said his government has "very serious concerns regarding allegations about unethical means used" to secure the 2010 deal.
"I have sought full assistance from the UK in this case," said Singh.
"Prime Minister David Cameron has assured me of the cooperation of his government in the investigations."
Cameron is India in an attempt to persuade politicians and business leaders to boost ties with the former colonial power.
During his meeting with Sing, Cameron lobbied the prime minister to open up its economy to foreign investment to allow retailers, such as Britain's Tesco, to open outlets there amid frustration that many of the sectors in which UK business excels remain partly or fully closed to foreign investors.
Cameron's delegation, which includes representatives of more than 100 companies, cultural and educational bodies, is the biggest taken abroad by a British prime minister and includes four ministers and nine politicians.
At a time when Britain's government is struggling to grow its economy, officials see India, projected to become the world's third largest economy by 2050, as a key strategic partner in what Cameron has called a "global race".
For now, Britain's economy is the sixth largest in the world and India's the 10th.
India is forecast to spend $1 trillion in the next five years on infrastructure and Britain is hoping its firms may win some of those contracts.
Cameron on Monday said he wanted his country's companies to help India develop new cities and districts along a 1,000 km corridor between Mumbai and Bangalore, generating investment projects worth up to $25bn.
The government also plans to build 24 new industrial cities along a 1,500km railway line between New Delhi and Mumbai with Japanese funding, but the project has progressed slowly.
Cameron also announced that his country will issue same day visas to Indian businessmen willing to invest in the UK.