DARJEELING, India (AFP) - Indian police on Thursday (June 22) charged a separatist leader and his wife for their involvement in a murder and arson, after his group warned of escalating violence as tensions rise in Darjeeling.

The picturesque hill station has been reeling from deadly separatist unrest that has forced shops and businesses to shut and caused tourists to flee.

As the violence escalated sharply last Saturday, police said one man died as protesters torched cars and set upon security forces with knives, who responded with tear gas and baton charges.

"Police have lodged a case against Bimal Gurung and his wife Asha for their alleged involvement in violence, arson and killing of a person during clashes," Inspector General Anuj Sharma told AFP.

"The investigation is on," he added.

Gurung's Gorkha Janmukti Morcha (GJM) - a separatist movement that has long called for a new state of "Gorkhaland" to be carved out of West Bengal - claimed three of their men were shot dead by security forces in the clashes, which police have denied.

"Three of our supporters were killed and they are filing cases against us," said GJM's general secretary Roshan Giri.

"Cases should be lodged against the police and state administration for violating human rights and killing," he told AFP.

The GJM has warned its indefinite strike called earlier this month could degenerate into more violence.

The separatist movement has given local schools 12 hours to evacuate their students and shut down on Friday.

Gurung told reporters on Wednesday that except school buses, no other vehicle would be allowed to leave the area during the 12-hour "window".

The hills are famous for the Darjeeling tea whose production is jealously guarded. It is also famed for its "toy train" - a 78-kilometre uphill ride from New Jalpaiguri.

Dozens of people including police have been injured in the riots that have rattled the area for nearly two weeks.

The latest violence was sparked by a government proposal to teach the Bengali language in schools in the predominantly Nepali-speaking area.