British Airways will accept sky marshals on flights if they can be shown to improve passenger safety.
BA's chief executive, Rod Eddington, said yesterday that an armed police officer might have a place in aviation security in the "current climate" and managers were drawing up a protocol for their use.
"Our position at British Airways is that if indeed security on a particular flight could be enhanced by the onboard presence of an armed police officer, we would be happy to accept that fact," Mr Eddington said.
"Equally, we maintain that if we have any cause for concern regarding the safety or security of a particular flight, we would simply not operate [it]."
Mr Eddington said a BA flight from London to Washington had been delayed by up to three hours last week because of security checks by the US authorities.
"I am a fan of vigilance, and British Airways makes no apology for its strict security measures. But I am not a fan of needless bureaucracy. Last week's delays were due, in part, to the fact that a total of 22 different agencies claimed a reason to check one passenger list."
BA was working with the US government to streamline the process, said the airline's chief.
KLM Royal Dutch Airlines said yesterday it was planning a six-month trial of sky marshals. "We want to see the marshals carrying new, smart weapons such as rubber bullets that cannot pierce the shell of the aircraft," a KLM spokesman said. "We are prepared, under certain conditions, to allow them on board."
Last month, the US Department of Homeland Security said that airlines would be required to have armed law enforcement officers on flights to the US "where necessary".
Jim McAuslan, general secretary of the pilots' union Balpa, said he was still discussing the deployment of sky marshals with the Government. He said: "It will apply to all airlines. Until we have a protocol our advice to our captains is not to fly with a sky marshal on board."
Mr Eddington revealed that last October the RAF scrambled two Tornado fighter jets to Heathrow airport when it was feared that an incoming service from Baltimore faced a hijack attempt.
But the two men who were reportedly overheard saying "we've been planning this for six months - let's do it" were debating the merits of a family reunion with a long-lost aunt.