Photo taken on Sept 22, 2013, the?World Car Free Day,?shows the crossroad of Guomao area at the evening rush hour in Beijing, capital of China. [Photo/Xinhua]

SHENZHEN -- Authorities in Shenzhen announced a car purchasing restriction requiring prospective buyers to acquire new car plates by lottery or auction on Monday.

Starting from 6 p.m. Monday, 100,000 new vehicle plates will be allocated annually for the city, including 20,000 electric cars, said Chen Huigang, deputy director of the city's traffic and transport commission.

The number may be adjusted later based on road capacity and air pollution, Chen said.

Half of the plates will be distributed through lottery and the other half by auction, he said.

In the future, the auction may be connected with carbon emission trading, he said, not offering any details.

Xu Wei, deputy head of traffic police bureau of the city, said vehicles with non-Shenzhen plates will be forbidden during rush hours on weekdays if they are not from Hong Kong or Macao.

The number of vehicles in Shenzhen exceeded 3 million by September.

Shenzhen, in south China's Guangdong Province, is the eighth city to adopt purchase restrictions following Beijing, Shanghai, Guangzhou, Tianjin, Guiyang, Shijiazhuang and Hangzhou, as traffic congestion has become a common headache for residents in many Chinese cities.