LONDON, England (AFP) — The Olympic Athletes' Village opened its doors yesterday to the first competitors as the logistical operation to handle the arrival of thousands of athletes and officials shifted into a higher gear.

London's Heathrow Airport was expecting to handle a record number of passengers, with the Olympics arrivals swelling numbers to almost 237,000 at the west London hub, compared to 190,000 on an ordinary day.

The first priority "Games Lane" went into operation on the M4 motorway leading from Heathrow, to allow athletes and officials to be whisked to their destinations without being delayed by London traffic.

It emerged that nine police forces have had to deploy extra officers to help with security for the Games, a week after the government was forced to draft in 3,500 troops to meet a shortfall in private security guards.

At Heathrow, where passengers have complained of being stuck in passport queues for several hours in recent weeks, the addition of extra border officials appeared to have eased the process.

There were few complaints from spectators or athletes, who were greeted by more than 500 volunteers as they landed.

The Netherlands women's beach volleyball team flew in from Amsterdam in a blaze of orange tops and said they were impressed by the setup.

One of the players, Marleen van Iersel, 24, told AFP: "From the moment we walked off the plane there were people helping us straight away. It is very well-organised."

A large US contingent also arrived at Heathrow, including members of the sailing teams.

But experiences of the early arrivals were mixed, with two-time world 400 metres hurdles champion Kerron Clement claiming the bus ferrying him and his US teammates from Heathrow to the Athletes' Village had taken four hours.

Clement tweeted: "Um, so we've been lost on the road for 4hrs. Not a good first impression London.

"Athletes are sleepy, hungry and need to pee. Could we get to the Olympic Village please."

However, the hurdler later tweeted to praise facilities at the athlete's village, located in the Olympic Park in Stratford, east London.

"Eating at the Olympic village," he wrote. "Love the variety of food choices., african, caribbean, Halal cuisine, india and asian and of course McDonalds."

London Mayor Boris Johnson shrugged off the incident, joking that it had given the athletes "even more of an opportunity to see even more of the city than they might otherwise have done."

Competitors and officials will be accommodated in 2,818 apartments across 11 residential blocks, each built around a courtyard offering athletes space to relax.

Organisers could do nothing though about the grey skies and persistent drizzle in London as athletes got a first taste of their home for the next three weeks.

The Australian team have already taken over several balconies of one block, with a banner reading "Aussie, Aussie, Aussie; Oi, Oi, Oi" draped across them.

The furore over the giant private security firm G4S showed no signs of abating, despite ministers' insistence that the Games would be secure.

G4S has insisted that the extra police drafted in should be able to withdraw in the next few days.

"This situation is being rectified over the coming days, which should lead to the withdrawal of police officers from those roles assigned to private security," a G4S spokesman said.

In a heated parliamentary debate on the security issue, Home Secretary Theresa May said it was "untrue" that ministers knew last year that there would be a shortfall in the numbers of security personnel they had been promised.

"G4S repeatedly assured us that they would overshoot their targets," she said.

Shares in the company, which says it is likely to lose £50 million (US$78 million, 63.5 million euros) over the debacle, dived 10 per cent in early trading in London before recovering slightly to close down 6.66 percent.

What is billed as the biggest anti-doping operation in Olympic history also got under way on Monday.

Half of all competitors will be tested, with a team of 150 scientists taking more than 6,000 samples between now and the end of the Paralympic Games on September 9.