Paula Radcliffe saw her Olympic dream vanish for a third time last night as she broke down in the gruelling Athens marathon.

The British running heroine's brave bid for gold ended in tears as she dramatically dropped out of the toughest of road races only three miles from the finish.

Exhaustion in the searing 35C heat was blamed as the athlete, who pushed herself to the very limits of human effort, missed out on a medal for the third Olympics in a row.

Fans around the world had to witness heartbreaking scenes as Radcliffe bravely tried to continue after stopping but broke down again moments later.

She faltered yards short of the 36 kilometre mark, struggled to get her rhythm back, then collapsed in tears at the roadside.

She was robbed of entering the historic Panathinaiko Stadium where hundreds of British fans were waiting to cheer her to glory.

Instead, she quietly slipped away 90 minutes later holding the hand of husband and trainer, Gary Lough, and looking pale.

Asked how she felt, she simply said: "Devastated."

A spokesman for the British Olympic Association described her as "emotionally and physically drained and very, very tired".

Fans who travelled to Greece in the hope of seeing the greatest female marathon runner fulfil her destiny were left sorely disappointed.

Andrew Stroud, 34, from Beckenham, south-east London, said there was "a huge intake of breath" in the stadium when Radcliffe pulled up.

"That's the beauty of sport, the pain as well as the pleasure," he said. "It's very painful right now."

John Parker, 36, from Guildford, Surrey, said: "It's an absolute shocker. I'm disappointed for her and disappointed for Great Britain."

A 30-strong party of British schoolchildren, guests of the Mayor of Athens, on an exchange trip to Greece, were equally disappointed.

James Swift, 15, from Wright Robinson Sports College, Manchester, said: "It's devastating. I'm so disappointed because she wins all the time normally, and everyone was expecting her to win."

The running ace was more than two hours into the event, and in fourth place when she stopped.

She was losing ground in the blistering heat after completing about 23 miles of the 26.2-mile event.

Initially a front runner and slipping into her familiar "bobbing head" running style, she was still ahead at the halfway mark.

But at 25km Japanese athlete Mizuki Noguchi and Ethiopian Elfenesh Alemu made a break and Radcliffe never made up the gap, despite a Herculian effort.

Noguchi won the race with 2hrs 26mins 20secs, just ahead of Kenyan Catherine Ndereba. Bronze went to American Deena Kastor.

Before the race, Radcliffe, from Bedford, wore a specially designed Nike pre-cool vest for 30 minutes to keep her body temperature low.

That should have allowed the 30-year-old runner to perform to maximum capacity over the demanding course where the first 22 miles had many energy-sapping climbs.

Dr Clive Williams, professor of sports science, said the effects of dehydration would be exacerbated in the searing Athens heat.

"The killer is the humidity," he told BBC News 24.

"In reality once you get into these conditions, it is a complete surprise, it feels like one is running in warm water."