North Korea has banned foreign runners from participating in an international marathon scheduled to be held in the capital in April, citing fears about the spread of the deadly Ebola virus.

North Korea is thousands of miles from the epicentre of the Ebola outbreak in West Africa and has reported no cases of the virus, which has killed more than 9,000 people.

Nonetheless, its borders have remained closed to foreign tourists since last October, for fear the virus might spread, and it imposes a strict 21-day quarantine for foreign aid workers and diplomats, who have been told to stay in embassy compounds.

"Our North Korean partners in Pyongyang contacted us this morning with news that the 2015 Pyongyang Marathon has - as of today - been closed to amateur and professional foreign runners," Nick Bonner, director of Beijing-based Koryo Tours said.

Young Pioneer Tours, another China-based tour agency which takes Western tourists into North Korea, confirmed the ban.

Pyongyang, the isolated and secretive country's capital, has held an international marathon most years since 1981. Foreign amateurs were allowed to compete for the first time last year.

"We were told that this is due to the ongoing precautions that the country has put in place in relation to fears held there over the Ebola virus," said Mr Bonner.

He said Koryo Tours had expected to take up to 500 people to North Korea for the marathon, which would have been his largest-ever tour group.