Finance Minister Arun Jaitley on Friday said all political parties must take note of the “dangerous tendency” of Maoists expanding their activities and also attacked some political parties using Maoist forces against the National Democratic Alliance.

Jaitley’s comments come a day after Pune Police claimed to have found a letter at the home of one of the activists they arrested on Wednesday, which hints at a plan for “another Rajiv Gandhi-type incident”. Five social activists were arrested on suspicion of having links with the banned Communist Party of India (Maoist).

“The Maoist believe in the violent overthrow of constitutional system and not just the government,” Jaitley said in a post on Facebook. “In their perceived system there are no fundamental rights, no rule of law, no Parliament and no free speech. But to expand their political base their sympathisers make full use of the democratic idioms.”

Recalling a discussion in the Rajya Sabha during the United Progressive Alliance’s second term, Jaitley said there were four kinds of Maoists – ideologically indoctrinate, weaponised Maoists who carry out the operations, innocent tribals who have been misled to believe Maoists will get them relief, and “half Maoist”.

Referring to “half Maoist”, he said, “They masquerade as activist; they speak the language of democracy; they have captured the human rights movement in several parts of the country but always lend support to the Maoist cause.”

He further said that some political parties “see the Maoist as their instrument in the anti-NDA cause”. “Never ride a tiger, you may be its first victim,” he said.