Kathmandu, March 27 : The smoke from increasing wildfire mixed with haze haze covered the sky of Nepal's capital Kathmandu, leading to the diversion of international and domestic flights due to poor visibility. Thick haze hung over Kathmandu's sky from 2 p.m. on Friday decreasing the visibility below 800 metres, Xinhua news agency reported. For a plane to take-off, around 1,600-metre visibility is considered appropriate. "We had to divert the domestic and international flights for the lack of needed visibility for the landing," Deo Chandra Lal Karna, spokesperson at the Tribhuvan International Airport told Xinhua. A record 479 wildfire incidents were reported on Thursday, according to Sundar Prasad Sharma, an under-secretary at the Department of Forest and Soil Conservation As the air quality deteriorated, the Himalayan nation's capital became the most polluted city in the world on Friday afternoon, The Kathmandu Post newspaper said in a report. Nepal witnessed a relatively hot and dry winter as the country received only 25 per cent of normal rainfall in the season. With scant rainfall in three winter months (December-February), the country experienced a severe drought-like situation, the report added. /IANS