WHO Director-General Tedros Adhanom Ghebreyesus was quoted as saying by CNN that two scientists of the United Nations team had already left their home countries for Wuhan when they were told that Chinese officials had not approved the necessary permissions to enter the country. 

The WHO chief siad he was 'disappointed' with the development.

"I am very disappointed with this news," Tedros was quoted as saying by CNN during a news conference in Geneva on Tuesday.

He said: "I have been in contact with senior Chinese officials and I have once again made clear that the mission is a priority for WHO and the international team." 

Tedros said WHO was "eager to get the mission underway as soon as possible" and that he had been given assurances that Beijing was speeding up the internal procedure for "the earliest possible deployment."