BANGALORE (AFP) - Doctors in India smuggled a desperately ill patient across state borders under cover of darkness to receive a liver transplant after the police said violent protests would make a journey by ambulance too dangerous.

Police halted traffic between the southern states of Tamil Nadu and Karnataka after protesters angered by water shortages began rioting and torching vehicles.

The move forced doctors at a Karnataka hospital to come up with an alternative plan after a liver for transplant became available for their patient at a hospital in Tamil Nadu.

Dr Arikichenin Olithselvan, a doctor at the Manipal Hospital in Karnataka, said they had to ditch their ambulance and wheel the 55-year-old man across the border before finding a local ambulance to ferry him to the hospital where the operation would take place.

"We had to take out the patient from ambulance and put him on a wheelchair," he told AFP on Friday (Sept 16).

"They (police) did not want to take chance in allowing our ambulance with a serious patient cross the border."

Vehicles from both the southern states were stoned and burnt by protesters over the sharing of the Cauvery River water. Police have not been allowing even ambulances with Karnataka number plates to drive into Tamil Nadu across the tense border.

Thousands of police officers have been deployed in Karnataka and a curfew declared after protesters set buses and cars ablaze this week.

The protests erupted after the Supreme Court ordered Karnataka state to release water from a river to ease a shortage in Tamil Nadu until later this month.

Two people have been killed in the violence in Bangalore, which is known as India's Silicon Valley and is home to local IT companies as well as offices of international giants such as Amazon and Microsoft.

India suffers severe water shortages that cause frequent tensions between states and the row over sharing the Cauvery River, which starts in drought-hit Karnataka, stretches back decades.

Dr Olithselvan said the 12-hour transplant operation had gone well and the patient was recovering.