LONDON (Reuters) - Europe's biggest airline, British Airways, canceled a London-Washington flight Friday as security fears grounded a U.S.-bound plane for the seventh time in just over a week.

"It has been canceled, that was based on advice from the UK government for a security reason," a BA spokeswoman told Reuters.

Flight 223 was also grounded Thursday. Wednesday the same flight was held on the tarmac at Washington's Dulles International Airport. Passengers were questioned, but no one was arrested. [...]

Kevin Rosser, terrorism analyst at London-based Control Risks Group, said: "We are just in a world now where governments feel they have to act on scraps of information.

"I think you have to understand the position governments are in politically. If, God forbid, something terrible happens and then it emerges they had information of a risk but did not do anything, they would be totally exposed politically."

Asked why airlines did not simply remove suspect passengers and let the plane continue, he replied: "If you suspect one person is a threat, you don't know if that person is working with other people on the flight." [...]