Close to 50 million shares in Irish explorer, Petroceltic, changed hands in London over the past two days, with buying demand adding close to 40 per cent to its share price.

Investors yesterday bought 34 million shares in the company, which is listed on London's Alternative Investment Market (AIM). They had already snapped up 15 million the day before.

The buying spree added almost 40 per cent to the company's price over two days. It closed last night at 5.35 pence sterling (7.3 cents), up 1.45 pence on its Thursday opening price of 3.9 pence. It opened yesterday at 4.78 pence.

In all, around 10 per cent of the company's shares have changed hands.

It was not known last night if any individual or organisation acquired a declarable interest, that is 3 per cent or more, in the stock.

This is unlikely to emerge before next week, as any buyers have three days to declare such a purchase.

Last night, Petroceltic's managing director, Mr John Craven, said the company was analysing the trades. "We believe the interest was primarily on the back of a re-rating of the company by our broker, Davy Stockbrokers," he said.

During the week, Davy analyst Mr Job Langbroek issued a research note on the company that suggested a realistic valuation would be 18 pence.

This was based on the fact that the company is now focused on two "relatively low-risk" oil and gas prospects in the Celtic Sea and Tunisia.