Norway’s Songa Offshore has filed $65.8m in counterclaims against Daewoo Shipbuilding and Marine Engineering (DSME), in a dispute over semi-submersible rigs Songa Equinox and Songa Endurance.

The case arose in mid-2015 when DSME moved to sue Songa for $179m over its construction of Cat D rig Songa Equinox, and later $172m for sister unit Songa Endurance.

The Korean yard alleges Songa included “inherent errors and omissions in the design documents”, leading to cost overruns and additional work on the two rigs.

In a statement, Songa Offshore announced it would “vigorously defend the claims asserted by DSME.”

“Songa Offshore considers that DSME is solely responsible for the delays to the Rigs and any attempt by DSME to recover cost overruns has no merit due to the "turn-key" nature of the construction contracts,” the company added.

Both companies are suffering financially in the current climate of depressed oil prices. Songa Offshore has said it will close its office in Aberdeen and Korea, cutting its workforce by 200, while DSME recorded losses of $4.3bn and has announced plans to shed 12,000 jobs by 2019.