LAHORE, Dec 22: Thick fog blanketed plains of Punjab, including Lahore, on Thursday, increasing the intensity of cold and disrupting rail and air traffic.

In Lahore, fog began enveloping the city early Wednesday night, reducing visibility to only 20 metres at 6:25am. The fog never lifted completely during the day and started thickening again at around 8pm on Thursday.

According to chief meteorologist Shaukat Ali Awan, several other cities, including Bahawalpur, Sargodha, Jhelum, Faisalabad, Sheikhupura, Sialkot, Sahiwal, Rahim Yar Khan and Multan were also shrouded in fog.

Foggy weather, he said, was also affecting the Indian Punjab and Uttar Pradesh, and would persist for the next three days.

Mr Awan said a cold front from the west that was accompanied by calm wind had increased humidity and excessive air pollutants had formed fog, which would be cleared only after a rain or a strong wind.

The Met office at the airport said the fog had reduced visibility to just 30 metres at 3am last night, which further decreased to 20 metres at 6:25am. The visibility started improving at 9:25am on Thursday, but it could not improve beyond 800 metres throughout the day.

The maximum temperature in the city was 17 degrees Celsius and minimum 2.8 degrees Celsius with 92 per cent humidity in the morning and 77 per cent in the afternoon.

The Met office has forecast more fog in Lahore and elsewhere in Punjab during the next 24 hours.

TRAFFIC: Fog disrupted rail and air traffic, delaying the arrival of at least 10 major trains and either delayed take-off or forced diversion of 16 domestic and international flights to Lahore.

The arrival of almost all upcountry trains was delayed by two to seven hours.

Freight and container trains were also delayed.

Meanwhile, many flights of Pakistan International Airlines for various destinations abroad were delayed. Heavy mist also forced cancellation of many domestic flights.