Union leaders have told an inquiry into offshore helicopter safety that operators are subject to commercial pressures.

MPs on the Commons Transport Select Committee questioned representatives from helicopter operators, manufacturers, trade unions and industry bodies during an evidence session at the University of Aberdeen.

The committee's inquiry was set up after last year's fatal Super Puma L2 crash off Shetland. Members are looking at measures that might curb the risks offshore workers face from helicopter transport.

Four oil workers were killed when their helicopter plunged into the sea on August 23. Fourteen people survived.

John Taylor of Unite union said workers still did not feel able to raise safety concerns, and that, in the wake of the crash, unions had received hundreds of emails from concerned workers.

He said: "Everyone says you can refuse to do the job. As trade union officials we represent people who have refused to do the job and then they are suddenly dismissed. There is an environment still offshore where people have concerns about raising safety issues. This is an issue offshore and it's a concern offshore.

"And I believe that commercial pressure is operating in the industry."

Steve Todd, national secretary of the RMT union, said: "We believe there are commercial pressures. We can't prove it categorically but as we've said in our submission a public inquiry or judicial review looking into every aspect of the operation might tell us differently, and that is why we've called for that public inquiry."

But the claim was disputed by Mike Imlach, director of Bristow Helicopters, who said: "I can honestly say we've never been under commercial pressure where we've felt it's unsafe to continue a flight.