ConocoPhillips said on Wednesday that it had swung to a huge quarterly loss after taking a $34bn writedown as falling oil and gas prices continue to take their toll on asset prices.

The US’s third-largest oil group had warned of the writedown, as well as 1,300 staff lay-offs and a reduction in capital spending this year to $12.5bn, from $15.3bn in 2008, in an interim report several weeks ago.