TOKYO (AP) — North Korean authorities are barring foreigners from this year's Pyongyang marathon, a popular tourist event, amid ongoing Ebola travel restrictions, the head of a travel agency that specializes in the country said Monday.

Nick Bonner, co-founder of Beijing-based Koryo Tours, said more than 400 foreign runners had signed up with his agency alone for the event, which is to be held April 12. He said he was informed by officials on Monday that the race would be open only to local runners.

Though no cases of Ebola have been reported anywhere near North Korea, the country shut its borders to foreign tourists in October with strict regulations to keep the virus out. North Korean media have suggested Ebola was created by the U.S. military as a biological weapon.

Bonner, speaking with The AP by phone from Beijing, said he remains hopeful the Ebola restrictions will be lifted by the end of next month. But he said marathon organizers were probably still concerned that the large number of foreign tourists might pose a problem considering the lingering level of worry over the spread of the virus in the North.

He said he did not think the decision reflected any deeper problems in the North's secretive and often enigmatic government.

Last year's race through the streets of Pyongyang — which includes a 10-kilometer and half marathon along with the full course — was opened up to foreign recreational runners for the first time and was a big success. Elite runners from around the world are also usually brought in for the main event, but Bonner said they apparently won't be allowed in this year.

Since the Ebola measures were announced last October, visas for nonessential travel have been halted and, regardless of country or region of origin, all foreigners allowed in are technically subject to quarantine under medical observation for 21 days.

That includes diplomats and international aid workers, though they are allowed to stay in their residences or diplomatic compounds. It is not clear how strictly those rules are being enforced, particularly along the Chinese border, but even senior North Korean officials returning from trips abroad have been subjected to quarantines.

The travel ban has been a disaster for travel agents.

Despite its wariness of the outside world, North Korea has made a concerted effort to bolster its tourist trade in recent years by setting up special tourism zones and developing scenic areas and recreational facilities. The push is aimed primarily at Chinese tourists. Tens of thousands of Chinese tourists visit each year, according to Koryo Tours, while only a few thousand go from other countries.

Bonner said the group that had signed up for the marathon this year was the biggest his agency has put together in 10 years, and would have been one of the largest groups ever.