LONDON (Reuters) - Athletics great Haile Gebrselassie warned Britain's double Olympic and world champion Mo Farah on Friday not to make a premature switch from the track to the marathon.

Farah added the world distance double to the one he achieved at the 2012 London Olympics when he won the 5,000 and 10,000 metres at the recent world championships in Moscow.

He is only the second man, after Ethiopia's Kenenisa Bekele, to hold all four titles simultaneously.

Farah's track future, however, is uncertain with a first full marathon pencilled in for London next year, having run half the race in the capital earlier this year.

Gebrselassie, a multiple Olympic and world champion over 10,000 metres as well as a former marathon world record holder, cautioned against a switch to the road and said Farah should concentrate instead on breaking records on the track.

"I would like to advise him to stay a little bit longer on the track," the Ethiopian told ITV News London ahead of Sunday's Great North Run where both runners as well as Bekele will compete.

"Very few athletes are successful in this business from track to road. It looks like it is (too soon for him) but I don't know maybe I make a mistake.

"But if I run 3.28 for 1,500 metres why do I need to move to the marathon? I stay at 5,000 and 10,000 because there is a chance to break world records."

Gebrselassie said he made a mistake in switching to the marathon too early in 2002 and immediately returned to the track after one race.

"After one marathon I stopped because I was not that good. The combination, the speed I had, instead of continuing I went back to the track," he explained.