London expects to earn £3.35 million from hosting top sports events this weekend as a warm-up to the London 2012 Olympics.

The economic boost is expected to come from visitors, athletes and sporting bodies heading to the capital for the world championships in triathlon and modern pentathlon plus a four-nation basketball tournament, according to a spokesman for the London mayor Boris Johnson.

Up to 10 million people internationally are expected to tune in to live broadcasts of the events.

New London-based sporting events in 2009, running in addition to traditional contests such as Wimbledon, have brought in £19 million, the spokesman said.

The busy weekend of sport includes the pentathlon World Championships in which 160 top pentathletes will compete at Crystal Palace - the first to be held in London since 1986.

They are set to include Britain's Olympic silver medallist Heather Fell.

There is also the triathlon World Championships Series in Hyde Park on Saturday, giving Britain's triathletes the chance to try out the 2012 venue.

Alistair Brownlee, who has won all three of the events he has entered in this series, is looking to make it four victories from four with a home crowd cheering him on.

The Game On basketball tournament between Great Britain, Poland, Turkey and Israel takes place at the O2 arena.

Olympic medallists Keri-Anne Payne, Cassie Patten and David Davies are also among the elite athletes set to compete in the inaugural Great London Swim at The Royal Victoria Dock on Saturday.

Swimmers of all abilities will have the rare opportunity to race against a field including Britain's best open water swimmers, Australia's Olympic golden girl Stephanie Rice, Olympic champion Larisa Ilchenko of Russia and Germany's Olympic medallist Thomas Lurz.

The event is part of Great Swim, a new series of one mile swims taking place throughout the UK.

Event director Colin Hill said: "Our vision for Great Swim was to inspire people into trying outdoor swimming for the first time as well having the world's best competing in the same event."

Simon Morton, UK Sport's senior events consultant, said: "We are delighted that these competitions are taking place in the UK this weekend.

"To hold these world class events - and indeed the subsequent events over the next couple of weeks - on home soil will not only aid the preparation of our athletes, but also event managers, officials and volunteers in the build up to the London Olympic and Paralympic Games."

Mr Johnson said: "This is a fantastic opportunity for Londoners to watch world-class athletes at some of the capital's finest sporting venues and the first real chance to experience action at future Olympic locations like Hyde Park.

"As London 'warms-up' to welcome the world in 2012, let's cheer on our GB athletes and 2012 hopefuls.

"I hope that events like this will inspire more young Londoners to get involved in sports activity, even inspiring future winners."