A thick blanket of fog engulfed Delhi on Thursday morning with the mercury dipping to 7 degrees Celsius, the India Meteorological Department (IMD) said.

Low visibility due to the dense fog was reported from several areas of the city, such as Brigadier Hoshiyar Singh Road, Anand Vihar and India Gate.

As per the IMD, while dense to very dense fog was witnessed in isolated pockets of Punjab, Haryana, Chandigarh, Delhi, and Uttar Pradesh, dense fog enveloped isolated places in Rajasthan, Bihar and Madhya Pradesh.

The visibility recorded at Delhi's main weather station at Safdarjung was 50 metres at 5:30 am. It was 25 metres at Palam, the Met Office said.

According to the IMD, 'very dense' fog is when visibility is between 0 and 50 metres, 51 and 200 metres is 'dense', 201 and 500 metres 'moderate', and 501 and 1,000 metres 'shallow'.

Several flights and trains were also delayed and diverted due to low visibility.

A passenger at Delhi IGI Airport, Vishal said, "I am coming from Dubai. The flight is delayed. It has been half an hour now. The fog is delaying the flights."

"We have to go to Kuwait. Our flight is delayed," another passenger from Punjab said.

Moreover, the weather department forecast that dense fog would hover in the city on Friday, Republic Day and the minimum temperature would remain at 7 degrees Celsius.

Noting the cold wave conditions in parts of north India, IMD, said, "Cold day to severe cold day conditions prevailed in many parts of Punjab, East Uttar Pradesh and Bihar; in some parts of West UP, Haryana, Chandigarh and northwest Rajasthan. Cold day conditions were also observed in isolated pockets of Delhi and southwest Madhya Pradesh."

Earlier on Tuesday, the Delhi Bharatiya Janata Party citing a report of the Centre for Holistic Development, an NGO working for the homeless, attacked the Aam Aadmi Party government saying that 180 homeless have died due to cold in the national capital. (ANI)