Heavy traffic moves along a busy road during the evening in New Delhi October 20, 2014. REUTERS/Vijay Mathur

NEW DELHI (Reuters) - India’s capital will soon ban private cars from its roads on alternate days, according to their registration numbers, in an attempt to improve air quality in the world’s most polluted city.

Smog has blanketed New Delhi this week, as countries try to thrash out a deal to fight climate change at a UN summit in Paris.

“Particularly in winter when the pollution is high, we will implement for some time odd-and-even-number vehicle operations,” Delhi Chief Secretary K.K. Sharma told reporters on Friday after an emergency meeting.

“We will make all efforts to start it from the first of January.”

The government will run extra buses and ask the metro rail network to increase its services to cope with more people, he said. It will also consider shutting down inefficient coal power plants.

Delhi Chief Minister Arvind Kejriwal said implementation would be a challenge.

“But something urgent needed to be done in view of the emergency situation,” he tweeted. “Lets assess after trying for a few days.”

The World Health Organization said last year India had 13 of the 20 most polluted cities in the world, and poor air caused hundreds of thousands of premature deaths each year.

The federal government is planning to force all commercial trucks more than 15 years old off the road from April and is reviewing how it checks vehicle emissions.