North Korea from Friday will block tourists from entering the country due to concerns about Ebola, travel agencies said.

Koryo Tours, a Beijing-based travel agency specializing in tours inside North Korea, said it has confirmed with multiple business contacts inside and outside North Korea that the border will be closed as of Friday due to perceived threats from the Ebola virus.

Pyongyang didn’t indicate when the border will reopen, an official at the agency said, asking not to be named.

Young Pioneers Tours, another China-based tour operator that leads trips to North Korea, also said its tourism contacts inside North Korea confirmed the border closure from Friday. The agency was told that the closure would be until Ebola concerns are eliminated, Chris Kelly of Young Pioneer said.