New Delhi: The Delhi government may bring back the odd-even scheme to restrict the number of cars on the road in view of the increase in pollution levels, Transport Minister Kailash Gahlot has said.

The minister yesterday wrote to the Delhi Transport Corporation (DTC) and senior officials of his ministry, asking them to be "fully geared up" for implementation of the odd-even scheme "as and when" it is announced.

"With the increase in pollution levels in Delhi, the government may have to resort to emergency measures, including the odd-even scheme," he said.

The scheme, based on the last digit of the vehicle's registration number of vehicles, was implemented twice in 2016-- from January 1-15 and April 15-30. Under the scheme, odd and even numbered vehicles ply on alternate days.

It can be implemented when air pollution levels are in the 'emergency' category for 48 hours or more.

Last week, the Supreme Court-appointed Environment Pollution Control Authority (EPCA), a body empowered to enforce the Graded Response Action Plan (GRAP), had said it would not hesitate to enforce the 'odd-even' plan, order cars off roads, and shut schools if needed.

GRAP was notified by the Centre in January this year following an order by the apex court in November 2016.

According to Gahlot, procurement of additional buses by DTC would be the "main component" of readiness in case the odd-even scheme is implemented.

A major challenge in implementing the scheme is poor public transport facilities, despite a well developed Delhi Metro network.

The DTC has a fleet of around 4,000 buses, while the Delhi Integrated Multimodal Transit System (DIMTS) runs over 1,600 buses under the cluster scheme. Experts estimate that the city needs about 11,000 buses to cover all areas.

EPCA has already taken tough measures like shutting the Badarpur thermal power plant and brick kilns and banning generators after air pollution levels hit the 'Very Poor' and 'Severe' categories.