New Delhi: The Maharashtra police on Friday said it found "incriminating evidence" against the five arrested activists during the raids on Tuesday that hinted at a conspiracy by Maoists to overthrow the Narendra Modi government with a "Rajiv Gandhi-like incident".

Sudha Bharadwaj, Gautam Navlakha, Arun Ferreira, Vernon Gonsalves, and P Varavara Rao were arrested on Tuesday for their alleged links to banned out CPI Maoist.

ADG Parambir Singh, at a press briefing on Friday, an email letter between Rona Wilson and a CPI-Maoist leader spoke of the alleged assassination plot. Human rights activist Rona Jacob Wilson was arrested from Delhi in June in connection with the Koregaon-Bhima violence in Maharashtra in January this year.

“A protected communication between Rona Wilson and Surendra Gadling was recovered by police officers. Pune police were able to crack the protected password, which showed a conspiracy by the Maoists to overthrow the established government," he said.

He displayed the letter that spoke of ending "Modi raj" with a "Rajiv Gandhi-like" incident. "The letter also spoke of requirement of Rs 8 crore for annual supply of grenade launcher with four lakh rounds," he said.

He said police had also found thousands of minutes, mails, letters and other documents of CPI Maoists.

"The letter written by Rona to Maoist leader "Comrade Prakash" said: We have received your last letter regarding current situation here. Arun (Ferreira), Vernon (Gonsalves) and others are equally concerned about the urban front struggle," he said.

The letter asked Prakash to convey his decision, Singh said. "Comrade Kisan and a few other comrades have proposed concrete steps to end Modi raj. We are thinking along the lines of another Rajiv Gandhi (assassination)-like incident," Singh quoted the letter as saying.

Some of the letters exchanged between the arrested activists spoke of planning "some big action" which would attract attention, Singh said.

Delhi University professor G N Saibaba was arrested in 2014 on basis of similar evidence, including letters, he said. On the arrests of activists with alleged links to Maoists in June and earlier this week, the police officer said, "Police only moved to take action against these people when we were confident that clear links have been established between these overground activists and underground Maoists."

"The evidence in our possession clearly establishes their (arrested activists') links with Maoists, Singh said. Information obtained after seizure of such letters and other items shows the involvement of "overground" Maoist cadres in planning subversive acts, he said.

The arrests had led to outrage, with many civil rights bodies and activists calling it a “virtual declaration of emergency”.

The Supreme Court had on Wednesday said it would examine contentions that arrest of five civil rights activists in connection with Bhima Koregaon violence was an attempt at muzzling the voice of dissent.

A bench headed by Chief Justice of India Dipak Misra, as a major interim relief, had said these activists won't be sent behind the bars for now and will have to be kept under house arrest in their homes till the next hearing on September 6.

"Dissent is the safety valve of democracy and if you don't allow dissent, the pressure valve of democracy will burst," the apex court said as it issued notices to the Centre and Maharashtra government on the petition that has challenged the validity of arrests.

Writer-activist Arundhati Roy has alleged that the BJP will “try to derail everything” with “some surprise attack” in the run-up to the 2019 elections. Roy joined leading intellectuals and civil society members to demand action against Maharashtra police for launching a “vicious and malafide attack” against human rights activists.

A joint statement signed by Roy, lawyer Prashant Bhushan and activists Aruna Roy and Jignesh Mevani among others said the arrests “highlight the violation of all due procedures and are a mockery of the legal system”.

Launching a series of attacks on the Prime Minister Narendra Modi-led NDA government, Roy, a Booker-winning novelist and activist, asked people not to allow their "attention to stray from even when strange events befall us".