Shares in Tullow Oil dropped almost 4 per cent in Dublin yesterday after the exploration group said it had been forced to abandon two wells in Pakistan and Gabon after drilling failed to yield positive results.

In a statement to the stock exchange, Tullow said it had plugged and abandoned the Shahpur Chakar-1 well in Pakistan after all viable reservoirs proved to be contaminated with water.

In Gabon, it was also forced to abandon the Gryphon Marine-1 well after drilling yielded negative results.

The shares fell 25 cent, to end the day at €6.10 in Dublin. Meanwhile, in London they were down 5.3 per cent, or 23 pence, at 411.75 pence.

However, it wasn't all bad news. Tullow, which saw its profits almost quadruple last year, said natural gas production at one of its wells in Bangladesh, Bangora-1, had stabilised at 50 million cubic feet per day (mmcfd).

This drilling is part of a long-term production test to ascertain the size and connectivity of the reservoir discovered by the Bangora and Lamai wells in 2004.

The gas, the group's first in Bangladesh, is currently supplying the local market through the Ashuganj-Bakhrabad pipeline.

Tullow also said it will take another 40 days to ascertain the potential of Bangora-2, where it began drilling at the end of last month. The commercial ability of the field should be known by the end of the year once at least one more well has been drilled.

The company, which produces half of its gas in the UK, has several other drilling programmes on the go. It said yesterday that drilling had begun at its M'puta-2 well in Uganda last week and that testing of the Waraga-1 site was due to start at the beginning of next month. Last week the company also started drilling at the Banyan prospect in Equatorial Guinea.