Official sources said Japan, Ukraine and France have been allowed to operate flights between February 16 and 20 but India's request has not been approved.
When contacted, a Chinese Embassy spokesperson said there was no deliberate delay in grant of permission for the Indian flight to reach Wuhan.
"The current epidemic situation in Hubei province is complicated, and the prevention and control of Covid-19 has entered into a critical stage. There is no such thing as China deliberately delaying granting flight permission," spokesperson Ji Rong said.
The sources said Indian nationals stuck in Wuhan are waiting to be brought back home and the uncertainty over evacuation is causing them mental stress and anxiety.
The aircraft was to carry a large consignment of medical supplies to China and bring back more Indians from Wuhan.
Sources said while the Chinese side continues to maintain that there was no delay in granting permission for the flight to go, the clearance has "inexplicably" not been given.
In a letter to President Xi Jinping earlier this month, Prime Minister Narendra Modi conveyed India's solidarity to the people and government of China in meeting the challenge of the coronavirus
outbreak and offered to provide assistance to the country.
India then put together relief supplies in pursuance of Modi's commitment as a token of India's solidarity, particularly in the 70th year of the anniversary of diplomatic relations between the two countries.
"These supplies have been offered even as India faces tremendous shortage itself, given our ethos of helping others in their hour of need," said a source aware of the issue.
The items being supplied are gloves, surgical masks, feeding pumps and defibrillators based on the requirements as indicated by the Chinese side.
"The Chinese side always attaches great importance to the health and safety of Indian nationals in China, and provided assistance and convenience for the return of Indian citizens," Ji further said in reply to the query.
"We are carefully assessing the ground situation, as prevention work requires. Competent departments of the two countries are keeping communication and coordination in this regard," she said.
carrier Air India has already evacuated around 640 Indians from Wuhan in two separate flights.
According to estimates, over 100 Indians are still living in Wuhan. A sizeable number of countries have evacuated their citizens from China and restricted movement of people and goods to and from the country in view of the massive outbreak of coronavirus there.
Indian nationals in Wuhan continue their long wait for the flight. The delay is causing them and their family members in India tremendous mental anguish, said the sources.
They said relief and evacuation flights from other countries including by France are allowed to operate by China but the permission has not come through in India's case.
"Are they not interested in Indian aid provided as our token of support? Why are they creating roadblock in evacuating our nationals from Wuhan and putting them under hardship and mental agony?" said a person aware of the issue.
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