LONDON  (AFP) – Long waits to clear passport control at London Heathrow Airport can depend on which way the wind is blowing, Britain’s immigration minister said Tuesday.

Delays at the world’s busiest airport for international passenger traffic have triggered a furore in Britain as the clock ticks down to the July 27 opening of the London Olympics, for which Heathrow will be the main gateway.

Immigration Minister Damian Green said passengers from New York might well have to wait longer to go through if their flight arrives 10 minutes after one from Lagos in Nigeria rather than 10 minutes before.

“That will depend on the wind, over which, with the best will in the world, airlines and the Border Force don’t have the control,” he told the Home Affairs Committee, a parliamentary scrutiny panel made up of lawmakers.

BAA, the airport’s owner and operator, said some passengers had to wait up to three hours to get through Heathrow Terminal 4 last month.

Green said the queue lengths seen at some times of the day at Heathrow were “unacceptable”.

“This is a problem that we need to continue gripping.”

He said previous techniques for getting the queues down were not appropriate.

“The way in which queues had been mitigated over many years — five years or so — was to relax some checks in an unauthorised way when the queues got too big,” he said.

“So, in effect, we weren’t having risk-based controls: we were having queue-based controls.

“We are now taking the practical steps to address the issue of queues,” he said, on the basis that “the first priority absolutely has to be the security of our border”.