India's government has declared the Maoist faction of the Communist Party of India a terrorist organization.
The decision allows authorities to arrest any Maoist cadres or those deemed as sympathizers.
The central government announced the legal action as authorities in five eastern and central states braced for Maoist rebel attacks expected during a 48-hour general strike set to begin Monday. The rebels called the strikes in Bihar, Chhattisgarh, Jharkhand, Orissa and West Bengal.
The Maoists say they are fighting oppression, exploitation and corruption on behalf of India's poor and landless people.
They are said to control one-third of India's forests, from which they frequently attack police forces and target politicians.
Paramilitary forces were dispatched to the state of West Bengal last week to reclaim a rural town seized by the guerrillas.
Indian Prime Minister Manmohan Singh has said the Maoists are the gravest threat to India's internal security.
The insurgency has killed thousands of people in 13 of India's 29 states in the past few decades.
In West Bengal, the Maoist rebels are in open conflict with the non-violent Marxists, whose party members control the state government. Marxists politicians also run the state governments in Kerala and Tripura.
Prakash Karat, the secretary general of the Communist Party of India (Marxist), predicts the central government's action against the Maoists will not be effective.
He says the only way to combat the Maoists is through administrative and political measures.
More on this in Goutam Gupta's report from Kolkata.