Comedian Hiroshi Neko's hopes of competing in the men's marathon at the London Olympics could be in jeopardy after the International Association of Athletics Federations raised doubts over his eligibility to represent Cambodia, sources said.

The 34-year-old Neko, whose real name is Kuniaki Takizaki, was born in Japan and became a naturalized Cambodian citizen in late 2011 after competing in several international half-marathons there, which won him many fans throughout the country.

But the IAAF, world track and field's ruling body, has from this year changed the rules pertaining to athletes with new nationalities and no previous experience representing their adopted country in international competition.

One of the rules stipulates that if at least one year has not passed since the athlete gained nationality, the athlete must have continually resided in their adopted country or be given special permission by the IAAF executive committee.

There are doubts as to whether Neko has lived continuously in Cambodia since being naturalized, raising the possibility he may need to file an application through the Cambodian athletics federation for special permission to compete at the London games. The IAAF has asked the Khmer Amateur Athletics Federation to explain whether he meets the criteria, the sources said.

Vath Chamroeun, secretary general of Cambodia's Olympic committee, said last month that Neko would represent Cambodia in the men's marathon in London. He said that he had received official confirmation from the IAAF accepting Neko.

At an international half-marathon in Siem Reap in 2010, Neko finished third. Last year, he came in second in the first international half-marathon held in Phnom Penh.