Sydney  - Thousands of irate runners were urged Wednesday to join a class action after organizers admitted the 10-kilometre course at the national championships at the weekend in Melbourne was so short it was more like 9 kilometres.

"It's pretty appalling they can't get it right," said blogger Hitch on CoolRunning, Australia's most popular website for running enthusiasts. "Plotting it on Google maps/mapmyrun is enough to find that it's not quite right."

Others who measured the course at just 9.1 kilometres threatened legal action unless organizers of the Melbourne running festival offered a refund on the 60-Australian-dollar (54-US-dollar) entry fee.

International runner Mark Tucker, who crossed the line first in a personal-best time, realized before the finish that there had been a measuring mistake.

"We probably knew with, you know, 500 metres to go," he said.

Thousands of others who crossed the line elated at having racked up personal-best times learned their celebrations were as misplaced as the markers on the course.

Byron Koester was astonished to have clipped a full 4 minutes off his time when he entered the iconic Melbourne Cricket Ground, site of the 1956 Olympic Games.

"And then I asked my friend, and the poor guy had just beaten his previous record by 6 minutes, and when I said I thought it was only 9 kilometres he was pretty shattered," Koester said.

Event director Dallas O'Brien admitted to the short circuit.

"We apologize to anyone who may have been inconvenienced, and perhaps we should have highlighted the fact that they weren't 100- per-cent accurate," he said of the heavily discounted 5-kilometre and 10-kilometre courses.

O'Brien noted that the blue-riband event, the Melbourne Marathon, won by Ethiopian Asnake Fekadu, was exactly 42 kilometres and 195 metres. (dpa)