The loss, which was equivalent to 61.5 million euros, compared with profits of 79 million dollars in 2005, Cairn Energy said in its earnings statement.

Revenue climbed nine percent to 286.3 million dollars, but total production sank 13.0 percent to 24,523 barrels of oil equivalent per day.

"The group made a loss after tax of 82.0 million dollars, mainly due to the exceptional oil and gas write down of 71.5 million dollars as a result of the downward reserves revision on Sangu," Cairn said.

The Sangu field, offshore of southern Bangladesh, has been hit by falling output and drilling delays.

Cairn said on Tuesday that the total asset write-down relating to Sangu now stood at 213 billion standard cubic feet (6.39 billion cubic metres), compared with an earlier estimate of 187 billion that was given in January.

Estimated reserves at Sangu stood at 116 billion standard cubic feet. That was about 5.0 percent of Cairn's total booked reserves for 2006 compared with 6.0 percent previously.

Booked reserves refers to the amount of oil which a company believes it can recover from the ground.