NEW DELHI, INDIA - India's Maoist insurgency has spread to 20 of the country's 28 provinces, Home Minister Palaniappan Chidambaram said Monday, flagging it as a major security challenge for his government.

Opening a three-day meeting of top police officials in New Delhi, Chidambaram said 1,405 incidents of left-wing violence had claimed 580 lives so far this year across the country.

"Left-wing extremism purports to be a radical form of communism. Today, various groups adhering to this outdated ideology have their pockets of influence in 20 states across the country," Chidambaram warned.

The guerillas, whose shadowy leadership is based in the dense forests of central India's Chhattisgarh state, were refining their tactics and acquiring advanced military hardware, Chidambaram added.

In June, Chidambaram slapped a formal ban on the Maoist rebels, whose strength is variously estimated at between 10,000 and 20,000, officially designating them as terrorists.

The insurgency, which started as a peasant uprising in 1967, has been repeatedly flagged by Prime Minister Manmohan Singh as the main home-grown threat to security.

The rebels say they are fighting for the rights of neglected tribespeople and landless farmers.

In one incident last week, suspected Maoists abducted five railway employees during a rampage in the eastern state of Orissa in protest at the arrest of alleged sympathisers.

The guerillas also blew up train tracks and torched a police station. --AFP