As the capital reeled from three days of rioting and looting, Olympic organizers defended security planning for the London Games and pressed ahead Tuesday with sports competitions and meetings leading to next year's showpiece event.

A women's beach volleyball tournament began as scheduled at Horse Guards Parade, with players in bikinis competing on a sand court a short distance from Prime Minister David Cameron's 10 Downing Street residence.

But organizers decided to use two courts instead of one for Tuesday's 12 matches so play could finish nearly three hours early, allowing spectators and staff to leave before dark.

FIVB Beach Volleyball Director Angelo Squeo, who was on site during the Olympic Park bombing at the 1996 Atlanta Games, said he consulted with high-ranking London Olympic organizers and police before taking the decision.

"I will do whatever in order to not put in danger — not even risk putting in danger — anybody here," Squeo told The Associated Press.

A wave of violence and looting has raged across London, as authorities struggled to contain the country's worst unrest since race riots set the capital ablaze in the 1980s. More than 500 people have been arrested in London and over 100 charged so far.

England's exhibition soccer game against the Netherlands on Wednesday at Wembley Stadium — another Olympic venue — was called off to free up police for riot duty.

Cameron cut short his summer vacation in Italy and returned to London to deal with the crisis. He recalled Parliament from its summer recess and said 16,000 officers would be on the streets of the capital Tuesday night — almost tripling the number on the streets Monday night.

The image of the Olympic host city has been tarnished by the images broadcast around the world of buildings and vehicles in flames and looters running amok.

The disorder comes less than two weeks after London celebrated the one-year countdown to the opening of the games on July 27, 2012, with great fanfare.

On Monday, the violence spread to Hackney, one the boroughs encompassing the Olympic Park in east London. The unrest took place about four miles from the park, site of the main Olympic Stadium and other key venues.

"We have a commitment to deliver a safe and secure games and we will do so," Olympics Minister Hugh Robertson said. "All the evidence shows this trouble is low-level criminality driven by messages on social networks and not some new, emerging security threat."

The beach volleyball competition, which runs through Sunday, is a test event for the Olympic tournament that will be played at the same iconic venue next year.

"You'll have incidents anywhere you are in the world," U.S. player Brittany Hochevar said after a win over a Chinese team. "It doesn't matter. If you're in a big city, this could happen anywhere in the world, so this doesn't change my perception of London for 2012 or give me concern for the Olympics. That's the world."

Other scheduled test events this week include a cycling road race that will go through the streets of London on Sunday and a marathon swimming competition at Hyde Park on Saturday. The world badminton championship are taking place at the Olympic venue of Wembley Arena in north London.

"So far it's OK but we shouldn't go to the street alone — we should have company," Olympic champion Lin Dan of China said.

Olympic security officials said they are confident of their plans and have already taken public disorder into account as a potential risk.

"In light of the appalling events in London over recent days, we will review our planning to ensure that any lessons are identified," said Assistant Commissioner Chris Allison, the national Olympic security coordinator. "But first, we must fully establish the circumstances of what has happened and at this time it is too early to say whether our planning will significantly change.

"What is absolutely clear is that we are committed to the games being delivered in safety and security, for athletes, spectators and the wider public."

Hundreds of Olympic delegates from around the world gathered Tuesday at a hotel in Park Lane, near Hyde Park, to check on logistics for the games. The team leaders from more than 200 national Olympic committees were scheduled to tour the venues Wednesday.

"For sure it's not a good situation," Swiss Olympic team leader Gian Gilli told the AP. "Maybe it's good it happens now, not in one year from now just before the games. Everybody is aware this can happen every day and maybe next year too."

The U.S. Olympic Committee, which will be sending more than 1,000 athletes, coaches and officials to London next year, also expressed support for organizers.

"For every games we take security planning extremely seriously and work very closely with the U.S. State Department, the organizers and the local authorities to try to ensure the safety of our teams," USOC spokesman Patrick Sandusky said.

"We are confident in the security plans for the London Games and will continue to work very closely with LOCOG and the local authorities as we build towards the games in 2012."

In the Canary Wharf business district, top International Olympic Committee officials huddled with LOCOG leaders for a regularly scheduled "project review" of preparations for the games. LOCOG chairman Sebastian Coe and his team were meeting with a delegation led by Denis Oswald, the IOC executive board member who heads the coordination commission for the games.

The IOC reiterated its confidence in security planning for London.

"Security at the Olympic Games is a top priority for the IOC," spokesman Mark Adams told the AP. "While we are not responsible for security, we're happy with how local organizers are dealing with the issue and we are confident they will do a good job."

A year from Tuesday — Aug. 9, 2012 — will be Day 14 of the Olympics, three days before the closing ceremony. Among the medal events taking place that day will be the men's 200-meter and 800-meter finals at the 80,000-seat Olympic Stadium in east London.

Britain was already preparing a massive security operation for the Olympics, but most of the attention has been on the threat of international terrorism. About 12,000 police officers will be on duty each day of the games, which have a security budget of at least $770 million.


AP Sports Writer Stuart Condie and Associated Press writers Danica Kirka and Jill Lawless contributed to this report.