A cloud of dense fog hanging over the national capital led to the cancellation of several international and domestic flights on Thursday morning.

Speaking to rediff.com, senior Airport Authority of India officials said no landings and take-offs had been possible at the Delhi airport since morning.

Several international airlines have cancelled their scheduled flights from Delhi and moved their passengers to nearby hotels.

Domestic operators -- Indian Airlines, Sahara and Jet -- too have cancelled/rescheduled flights.

Flights from Mumbai, Kolkata and Chennai have either been delayed or diverted to Jaipur, Agra and Chandigarh.

Rail and road traffic has also suffered due to foggy conditions. Several trains were running well behind their schedule when reports last came in. Some trains scheduled to leave New Delhi in the morning may now depart only in the afternoon.

The meteorological office said foggy conditions would persist for another couple of days. Unseasonal rains that lashed the capital on December 31, experts said, have added to moisture levels in Delhi.

With vehicles virtually crawling on Delhi roads, traffic snarls have been reported at several busy junctions.