LONDON, July 26: British Prime Minister David Cameron led a chorus of apologies on Thursday at the London Olympics for the “honest mistake” of displaying the South Korean flag alongside photos of North Korean players before their match against Colombia.

As the hours counted down to Friday's opening ceremony, the flag flap wasn't the only issue for organisers.

A sprawling shopping mall next to the Olympic Park was briefly evacuated due to a fire alarm, officials at the Aquatics Centre were cranking up the air conditioning to bring down the heat for swimmers, and doping cost two more athletes their Olympic dream.

The greatest sporting show on earth will officially get under way on Friday, when around 80,000 VIPs and spectators will flock to the Olympic Stadium for an opening ceremony staged by Oscar-winning British movie director Danny Boyle.

However the sporting action was launched with the opening matches of the women's football tournament at venues across Britain on Wednesday, with their male counterparts entering the fray on Thursday.

The flag gaffe at Glasgow's Hampden Park led to the North Korean team refusing to take the pitch Wednesday for just over an hour and overshadowed the first day of Olympic sport as the women's football tournament started with six matches.

North Korea's Olympic representative Ung Chang expressed outrage and said it was a mistake that should not have happened.

“Of course the people are angry,” International Olympic Committee (IOC) member Chang said. “If your athlete got a gold medal and put the flag probably of some other country, what happens?

“I am really surprised how the London Olympic team, the protocol people, didn't invite someone from the team to check if it is your flag.”

The flag flap was raised again as Cameron visited the Olympic Park. The premier called the mix-up an “honest mistake” and said “every effort will be taken to make sure this won't happen again.”

Earlier, in response to a question from Chang on the final day of the IOC session, president Jacques Rogge said there had been no “political connotation”.

“The organising committee has taken corrective action and there will be no repeat. It was a simple human mistake,” he said.

Greece, who banned triple jumper Paraskevi Papachristou on Wednesday after a racist tweet, suffered further embarrassment on Thursday when the father of world indoor high jump champion Dimitris Chondrokoukis said his son had pulled out of the Games after failing a doping test.

Turkish weightlifters Fatih Baydar and Ibrahim Arat were suspended after failing drugs tests while Hungarian discus thrower Zoltan Kovago was ousted after refusing to undergo a doping control.

Speaking to reporters at the Olympic Park, Cameron said the government's priority was to ensure a safe and secure Olympics, with more than 9,000 extra police walking the streets and 17,000 troops called in to cover a shortfall left by private security group G4S.

“This is the biggest security operation in our peacetime history, bar none, and we are leaving nothing to chance,” Cameron said.

“Obviously the biggest concern has always got to be a safe and secure Games. That matters more than anything else.”

While doping and terror fears have been high on the list of concerns ahead of the Games, a sunny British summer has bathed the Olympics, much to the surprise of many Brits used to damp, cool conditions.

But as London bathes in sunshine, swimming coaches have complained that it is getting too hot in the Aquatics Centre.

Organizers said they are working with the air conditioning units to get the pool deck temperature down to 27 degrees Celsius (80 Fahrenheit).

With the opening ceremony just a day away, the Olympic torch was visiting the top tourist sites of London including the Houses of Parliament, Downing Street and Buckingham Palace, where it was to be greeted by Prince William and his wife Kate, Duchess of Cambridge.

The flame's 12,900-kilometre (8,000-mile) journey ends Friday night when the final torchbearer — whose identity remains a closely guarded secret — lights the Olympic cauldron.

After the opening ceremony on Friday, attention will quickly focus on the sport, with the progress of swimmer Michael Phelps no doubt dominating the first week of the competition as he battles team mate Ryan Lochte for supremacy in the pool.

Phelps, who won a record eight gold medals in Beijing, will attempt seven events before he retires — his career achievements demonstrating that individuals are still at the beating heart of the Games.

The highlight of the Games is likely to be the men's 100 metre final on Aug 5, when Usain Bolt and seven other men compete for the title of fastest man in the world.—Agencies