Imperial, which is focused on operations in Russia, said it was recommending the cash offer by ONGC VIdesh Ltd (OVL), the overseas arm of India's Oil and Natural Gas Company (ONGC).

Imperial floated in 2004 with a market value of about £2.5m. It was founded by Leeds businessman and lawyer Peter Levine, who is its chairman.

The pre-conditional offer is subject to approval from the Russian authorities.

Shareholders would receive £12.50 per share and Imperial would be de-listed from the London Stock Exchange.

Last month Imperial confirmed it had received two separate offers.

The second, believed to be from China's Sinopec, has not progressed although analysts believe a rival Chinese bid could push the price higher.

Mr Levine, a specialist in international corporate law, is the largest individual shareholder of the company with 6.1 per cent of its shares.

He was appointed chief executive and chairman when the company was formed, but handed over the role of chief executive in April 2007.

Earlier this year he stood down as chairman of steel firm Severfield-Rowen to concentrate on his Imperial commitments.

A Russian speaker, and of Russian ancestry, he was formerly Honorary Consul for the Republic of Kazakhstan in the UK and joint chairman of the British-Kazakh Society.