New Delhi, Sep 4 (IANS): The CPI-M Wednesday asked Gujarat Chief Minister Narendra Modi to quit and demanded his prosecution following charges by a jailed police officer that he had approved 'encounter killings'.

"The CPI-M demands that Narendra Modi should be prosecuted in the concerned cases and should forthwith step down from office," it said in a statement.

The CPI-M statement came a day after police officer D.G. Vanzara wrote a stinging letter accusing Modi and former Gujarat home minister Amit Shah of approving the killings of alleged terrorists in fake gun battles.

Vanzara, once known to be close to Modi, has been in jail since April 2007 on charges of killing terror suspects in cold blood.

The CPI-M also called for a Supreme Court supervised inquiry into a CD which refers to efforts by the BJP leadership to sabotage the process of justice in some of the criminal cases.

"In the meanwhile, the bail of Amit Shah should be cancelled," the Communist Party of India-Marxist said.

It said the letter written by Vanzara "confirms in the most direct way what was known to most citizens - that the killings were executed with the full knowledge and direction of those leading the Gujarat Government".

It said the letter proved that "encounter killings (were) an intrinsic policy of the Gujarat government against terrorism.

"Modi's numerous statements at the time justifying the killings fit in perfectly with Vanzara's defence."

It added: "This episode once again highlights the utter contempt that the BJP and its leadership, including Modi, have for the constitution of India and the law of the land."