Oisin Fanning's San Leon Energy, a London-listed oil and gas explorer, said it has received more than $200 million (€179 million) of orders for new shares to help complete its "transformational" acquisition of an indirect interest in a Nigerian offshore oil field.

However, the Irish company, where UK hedge fund Toscafund is the main investor with a 41 per cent stake, said that the orders were placed at 45 pence per share - less than half the price it had signalled in May when announcing the share sale.

Non-executive chairman

The company also said that former managing director of Shell Petroleum Development Company of Nigeria, Mutiu Sunmonu, is set to become its non-executive chairman. Mr Fanning, currently executive chairman, will become chief executive officer, it said.

Trading was halted in January under London’s junior stock market (AIM) rules, as the deal to acquire a 9.72 per cent interest in the OML 18 operations in Nigeria constitutes a reverse takeover of a larger company.

The deal is being backed financially by Toscafund, which is run by Martin Hughes, who is dubbed the nickname 'the Rottweiler' in the City of London for the sometimes aggressive investment style that the hedge fund adopts.