Super Puma helicopters should remain grounded until union safety representatives give their approval for flights to continue, the Rail Maritime and Transport (RMT) union said.
Two models of the helicopter are grounded this weekend following the latest report into the North Sea crash which claimed 16 lives earlier this month.
The RMT, which lost two members in the April 1 crash, welcomed last night's grounding but said 48 hours was not enough.
General secretary Bob Crow said: "Whilst we welcome the news that our demand that the Super Pumas should be grounded has been met, it is clear that 48 hours will not be enough and we repeat our call for the fleet to remain on the ground until all checks have been completed, evaluated and signed off by our safety reps.
"Anything else is simply gambling with people's lives."
Industry body Oil and Gas UK said 25 helicopters in the UK offshore fleet were affected by last night's decision.
It came after an Air Accidents Investigation Branch (AAIB) report released earlier yesterday which ordered further and "urgent" inspections on helicopter gearboxes.
The AS332L2 Super Puma, which was involved in the April 1 crash, was grounded along with the EC225LP Super Puma, the model which crashed in the North Sea on February 18 in an accident which all 18 on board survived.
Industry bosses will meet helicopter operators on Sunday to decide what additional steps to take in light of further details expected to come from the European Aviation Safety Agency.
In an initial report into the April 1 crash, the AAIB said the gearbox of the Eurocopter AS332L2 had suffered a catastrophic failure before crashing into the sea off the coast of Aberdeenshire.
