Armed police vehicles are seen on a road as they withdraw from the Urumqi Diwopu International Airport after a China-bound Afghan plane, threatened by a bomb, was denied to land in the city.[Xinhua]

A plane flying from Afghanistan to Urumqi,capital of northwest China's Xinjiang Uygur Autonomous Region, reported a bomb threat and was refused permission to land, Xinhua news agency said Monday, citing armed police sources in Xinjiang.

The sources previously told Xinhua the plane was hijacked. The Urumqi airport has received an order from the aviation authorities to deny the plane's landing in the city. Armed police and emergency vehicles, however, have rushed to the Urumqi Diwopu International Airport for emergency response.

The China-bound Afghan plane with Kam Airlines later landed on the airport of Kandahar city in southern Afghanistan Sunday night, said an official in Kabul International Airport.

The official who was reluctant to disclose his name said the plane scheduled from Kabul, the capital city of Afghanistan, to Urumqi has already landed on Kandahar airport.

"The plane would return to Kabul after two hours," he added.

The airport official said the plane made the unexpected landing due to some "mechanical problem".

Meantime, president of Kam Airlines, Zamarai Kamgar, told Xinhua that it is the first flight day for Kam from Kabul to Urumqi and the plane was refused by Kyrgyzstan to pass its territory.

The Boeing-767 plane was carrying more than 200 passengers, including five Chinese.

"The plane chose to land in Kandahar city at first step because weather condition in Kabul was not suitable at that time," Kamgar added.

"The plane has made landing efforts in Kabul airport, but failed. Maybe it is because of strong wind," a Chinese passenger named Pan Dongjie told Xinhua from Kandahar.

"Now all the passengers are asked to stay on board," Pan said. "I have known about the bomb threat. I want to leave the plane as soon as possible."

Kam Air was founded in 2003 as Afghanistan's first private commercial airline. It serves a number of international and domestic routes with six aircraft and 350 employees, it says on its website.