Officials in India’s western Rajasthan state are offering men and women a car and other cash prizes if they undergo sterilisation.

The government is concerned over the size of India's population, which is forecast to surpass China's by 2030.

Sitaram Sharma, the head doctor of Jhunjunu in western India, expressed the hope at least 20,000 men and women would undergo the sterilisation procedure.

"We want to promote sterilisation," Pratap Singh Dutter, the deputy chief medical officer of Jhunjhunu district in the north Indian state of Rajasthan, said. "Everyone who gets sterilised between today and 30 September will be entered into a lottery to win prizes."

The top prize is the Tata Nano, which is made in India and is billed as the world's cheapest car, while other prizes include motorcycles, televisions and food blenders.

India's total fertility rate - the number of children born on average per woman - of 2.588, based on 2010 figures issued by United Nations Population Fund (UNFPA), which indicates a rapidly increasing population.

However, the fertility rate has fallen since 1990 when it stood at 4.0, the United Nations body reports.