Delhi and other cities across northern India have been blanketed by the poisonous haze that hits each winter because of buildups of vehicle fumes.(Photo: AFP)

The start of a leading Asian Tour golf tournament was held up Thursday by toxic smog that has engulfed the Indian capital with hazardous levels of pollution.

Organisers of the four-day Panasonic Open India event said the tournament could be shortened if the pollution remains serious, as completing the event would be "a big challenge".

Delhi and other cities across northern India are blanketed by a poisonous haze each winter due to build-up of traffic fumes, industrial emissions and smoke from agricultural fires.

"The opening round of the Panasonic Open India was delayed due to poor visibility and weather conditions," an Asian Tour organiser told AFP.

The first golfers went on the course five hours late and some wore anti-pollution masks.

A photo posted on Twitter by the Asian Tour showed Bangladeshi golfer Mohammad Siddikur Rahman hitting a shot while wearing a face mask.

The amount of PM2.5 -- deadly tiny particles that get into the bloodstream and lungs -- soared to about 20 times the safe limit set by the World Health Organisation.

Delhi authorities closed all schools until Friday, banned construction and are only allowing cars on the road depending on whether the registration is an odd or even number.

The road rationing is meant to end on Friday, but Delhi chief minister Arvind Kejriwal said it could be extended.