India's capital city of Delhi has virtually shut down as air pollution hit "severe plus" levels, according to Indian government officials in its pollution control authority.

In several areas of the city, pollution levels were more than 50 times higher than the World Health Organization’s recommended safe limit. Forecasts say the poor air quality will continue into the week.

Toxic smog engulfed much of northern India on Monday and pollution readings in New Delhi hit their highest of this pre-winter season, after dense fog overnight.

Around 38% of the pollution in New Delhi this year has been caused by stubble burning - a practice where stubble left after harvesting rice is burnt to clear fields - in the neighbouring states of Punjab and Haryana, according to SAFAR, a weather forecasting agency under the ministry of earth sciences.

A thick, toxic smog has enveloped India's capital, home to more than 33 million people. One technology firm which monitors air pollution ranked New Delhi as the most polluted city in the world.

Many of the regulars at Lodhi Garden in New Delhi, one of the world’s most polluted cities, say they won’t let rising pollution levels deter their daily visits.

Delhi ’s government imposed the most stringent set of restrictions on the movement of vehicles and people as the toxic smog enveloping the Indian capital worsened on Monday. The city’s average air quality index was 457 in the morning,

India's capital was left gasping this week as air pollution smog reduced visibility to near zero and raised air quality levels more than 130 times safe limits.