Dangerous weather conditions caused the annual Head of the River Race (Horr) from Mortlake to Putney to be abandoned after boats filled with water and rowers tumbled into the river.

A record 3,750 rowers from all over Europe and the US came to the Thames on Saturday to race the 4.25mile Oxford and Cambridge Boat Race course in reverse.

Up to 100 of them are reported to have ended up in the cold, dirty water after their boats sank.

The weather deteriorated not long after the first boats set off and a strong north-easterly wind made some parts of the river dangerously rough.

After 45 of the 420 crews had set off, the race was called off, as boats started to fill with water and conditions were deemed unsafe.

A number of crews had to be pulled ashore and only 29 teams finished the race.

Cambridge University won, and although the results were not officially declared, their victory will stand them in good stead for the Boat Race on Saturday.

Mike Davies, 28, from Southfields, was watching the race. He said: "From where I was standing I watched a boat sink. The cox and the guy in the number one seat were both under water.

"Then, walking towards Putney Bridge I saw their boat being towed upside down. But it was great to see so many people gathering in Putney for the event."

In 2004 the race was cancelled because of bad weather conditions but this year was the first time the 81-year-old event has been abandoned midway through.

The start of the race had been delayed by 15 minutes after one crew got into difficulties at the outset and had to be taken off the river in a rescue operation. During the delay, the weather conditions deteriorated further.

Horr Hon. Secretary Dr Andrew Ruddle said: "The crowd was bigger than usual because, apart from the wind it was quite a nice, sunny day.

"When the crews started to get into difficulty the spectators rallied round and helped get them out of the water."

The crews came from the US, France, Spain, Italy, Germany, Hungary, Holland, Austria, Switzerland, Scotland, Wales and England.

Both the Italian national squad and this year's English national team were there to compete.