PGS has clinched an agreement to delay instalments and maturity of debt totalling $1.2bn.

But legal action remains a possibility if the Norwegian seismic survey vessel owner cannot bring a minority of rebel banks on board.

PGS called the agreement in principle an "important milestone".

All lenders involved in its $300m export credit facilities have signed up, as well as 81% of banks in its $350m revolving credit facility (RCF) and 62% of those involved in its $520m term loan B facility (TLB).