Organisers of a marathon running event in Qatar reportedly bussed in migrant labourers to try to make up the numbers in a world record attempt.

According to media reports, Al Sadd Sports Club took the action as it tried to break the world record for numbers of participants in the event which was staged on Friday.

However, the attempt to beat the 50,000 record was called off after numbers fell short despite what witnesses described as a large number of entries, mostly of South Asian appearance, running without proper kit. Some were wearing jeans and flip-flops, reports said.

The “Mega Marathon” was originally scheduled to take place on February 6 in time for National Sport Day, but was postponed and rescheduled for March 27.

One participant told Doha News that it was “one of the most disorganised and chaotic events I have ever had the displeasure of attending”.

Another was quoted as saying: “The worst part of all was that there was a large mass of labourers wearing jeans, flip-flops and no proper running equipment. Some labourers tried to leave but were turned back and were yelled at that they need to stay and cross the line.”

Mega Gonzales Cervantes, a spokesman for the club, told the UK-based The Telegraph that the event had asked companies to encourage workers “with decent jobs” to take part, but insisted it was voluntary and that proper running kit had been offered to them.

“If they didn’t want to run, we advised them to go to their buses,” he told the paper. “We wanted to keep the course clear, and for the course to look presentable.”

The race failed in the end to beat the record, with only 33,000 registered runners, including the labourers. Some participants claimed the real figure was far lower.

Nicholas McGeehan, a researcher on the Gulf for Human Rights Watch, said Qatar’s Athletics Federation should investigate these "very serious allegations immediately".