At least seven flights were diverted and many were delayed at the Delhi airport on Wednesday morning as low visibility conditions impacted operations, according to officials.

The national capital experienced the season's first dense fog on Wednesday with the visibility dropping to zero at the Delhi airport.

The India Meteorological Department (IMD) reported that very dense fog began forming around 5.30 am, resulting in a thick haze over different parts of the national capital.

Zero-metre visibility was recorded at the Indira Gandhi International Airport at 8.30 am with the Runway Visual Range varying between 125 and 500 metres at different locations, the IMD said.

One of the officials said six flights were diverted to Jaipur and one to Lucknow since 7 am due to bad weather.

The second official said some flights have been delayed and the visibility conditions are improving.

There were low visibility conditions in the city.

"By morning, a heavy layer of fog blanketed the city, reducing visibility to as low as 125 metres in certain areas," the IMD official said.

The Indira Gandhi International Airport (IGIA) in the national capital is the country's busiest airport and handles around 1,400 flight movements daily.

Meanwhile, the air quality remained in the "very poor" category for the 15th consecutive day, with a reading of 366 at 9 am.

Two monitoring stations, including Anand Vihar and Aya Nagar, reported the air quality in the "severe" category, according to the Central Pollution Control Board.

Humidity was recorded at 92 per cent at 8:30 am.

The weather department has forecast shallow fog for the day, with the maximum temperature expected to settle at 32 degrees Celsius.