It has been announced that two British Airways pilots, allegedly found over the company's alcohol limit, have resigned.

Captain William McAulliffe and first officer David Ryan were arrested at Oslo airport in early November, after failing breathalyser tests. Investigations into the conduct of a cabin crew member, Michele Giannandrea, are ongoing.

The news follows the passing of the Railways and Transport Safety Act in July, which gives the police greater powers to investigate incidents of alcohol misuse among aviation and maritime staff.

The problem has not just been confined to the airlines ? five London Underground workers were dismissed after more than 100 empty beer cans were discovered in the staff mess room.

They were among 15 employees suspended and charged with gross misconduct.

"All our staff are aware of the zero tolerance policy we have on alcohol and breaches of that policy cannot be allowed," said Ian Prosser, safety director at the Metronet consortium. "Zero means zero. Safety is our top priority and is not compromised under any circumstance."

But the RMT trade union said the three arrests were based upon circumstantial evidence. "None of these people were ever tested for drink and drugs and management have flouted their own rules," said a spokesman.