Oslo-listed Siem Offshore has posted a bigger loss for the first quarter despite stronger revenue.

The company said the deficit was $17.3m to 31 March, against $9.6m in the same period a year ago.

Revenue climbed to $107.4m against $70.8m, but last year's bottom line was boosted by a $10m gain in currency movements.

The contract backlog stood at $1.14bn at 31 March.

The fleet of 45 ships includes four in layup.

"The North Sea spot market for AHTS and PSVs remained soft during the first quarter," it said.

"More rigs are being re-activated in preparation for the upcoming spring and summer drilling campaigns; however, we believe there will still be an oversupply of AHTS vessels and PSVs and expect the market to remain challenging for several years."