The chief executive of the G4S security group acknowledged today in London that his company's failure to live up to its Olympic obligations has turned into a country-wide humiliation.

Quizzed by a panel of angry British lawmakers Tuesday over his company's failure to recruit enough people to guard the Games, Nick Buckles gave a grovelling mea culpa.

"It's a humiliating shambles for the country, isn't it?" asked Labour lawmaker David Winnick.

"I cannot disagree with you," Buckles said.

Buckles was hard-pressed to explain why his company had failed to inform officials until only two weeks before the start of the 2012 Olympic Games that its recruitment had failed, forcing the government to call in 3,500 extra soldiers and police from various forces to fill the gaps.

G4S says it expects to lose between $54 million and $78 million US on the contract, which is equal to about 12 per cent of its annual profit.

'This has not, nor will it, impact on the safety and security of these Games. That of course is our No. 1 priority.'—Sebastian Coe, London Games chief

Also Tuesday, many security guards didn't show up for work a day after two buses full of Olympians got temporarily lost on London's winding streets.

But London Games chief Sebastian Coe said preparations are going fine ahead of the July 27 opening of the Summer Olympics.

`'Let's put this in proportion," Coe told reporters. "This has not, nor will it, impact on the safety and security of these Games. That of course is our No. 1 priority."

Buses take wrong turn

A couple of buses carrying Olympic athletes from Heathrow Airport took a wrong turn and one of the special "Games lanes" that they travelled on forced other London drivers into a kilometres-long traffic jam.

The lost buses — one for Americans, another for Australians — touched a nerve. From the very start of the project, transport organizers have feared repeating the transport woes of the 1996 Atlanta Games, where one of the biggest problems was having bus drivers brought in from outside the city who didn't know their way around.

That allegedly happened Monday in London, even though Heathrow sailed through its heaviest passenger day ever with short immigration lines and plenty of help for Olympic travellers.

"First day. First arrivals. It's going to happen," said Jayne Pearce, head of press operations.

A soldier heads a security check at the main entrance adjacent to Westfield Stratford City Mall at the Olympic Park on Tuesday in London with the Games opening just 10 days away. (Stanley Chou/Getty Images)

Coe urged optimism, despite a Twitter storm that erupted when an American hurdler took to the social networking site to express his frustration for a four-hour bus ride from Heathrow to the Athletes Village.

"Apart from a mis-turning and a couple of tweets, we're in pretty good shape," Coe quipped.

"The majority of athletes got in in good shape and on time. When they were met by our village mayor and chief executive, they were busily tweeting, saying how much they were enjoying village life. Ninety-eight per cent of these journeys went without a hitch."

Coe also downplayed the complaints about traffic problems caused by the opening of a special Olympic traffic lane on the M4 highway from Heathrow into the city. He said despite one accident west of London, "the vast majority of people got through and it seems to be working quite well."

The Games lanes remain a contentious issue. Hundreds of London cab drivers blockaded the square outside Parliament on Tuesday, blaring horns and snarling traffic to protest their exclusion from the lanes.

The cabbies claim it will be all but impossible to ferry passengers around the city once most of the special lanes take effect July 25.

Rain causes extra challenges

Yet the weather may prove an even more intractable problem.

Coe said "we've got mops and buckets" to deal with the incessant rain that has soaked London for most of the summer. The ground at two key venues is waterlogged -- the rowing at Eton Dorney west of London and the equestrian at Greenwich Park, south of the Thames river.

"It is a problem," Coe said. "It is causing us extra challenges now."

Coe said organizers are resurfacing areas at the two venues, laying down temporary tracking for vehicles and spectators and putting up special tent shelters to keep the work force dry.

Although forecasters say the weather could clear in time for the start of the games, Coe noted that organizers have contingency plans in case it doesn't.

Extra competition days were built into the schedule "as a last resort" for rowing and equestrian. There is an alternate course available for sailing events at Weymouth, in southeast England, and Wimbledon has a retractable roof over Centre Court for tennis.

Olympic Park, however, still resembles a construction site, with workers laying cables, installing seats and landscaping grounds Tuesday.

Not to worry, Coe said.

"Our venues will be open on time," he promised. "There is still stuff to be done, but it's about dressing up. We'll be ready."

Meantime, Britain's Olympics minister, Hugh Robertson, said the deployment of soldiers at Olympic Park would give people "enormous reassurance."

Robertson, a former army major, said athletes are "incredibly reassured to see the armed forces on the gate."

The Olympics run until Aug. 12.