MUMBAI: Maharashtra police on Friday said the evidence they have collected in connection with the arrests of five Left-wing activists establishes their links with Maoists organisations.

Addressing a press meet here, Maharashtra police additional director general (law and order) Parambir Singh said there was "conclusive proof" to link the arrested activists to Maoists, adding a letter exchanged by an arrested activist spoke of planning a "Rajiv Gandhi-like" incident.

The letter also sought money for procuring grenade launchers, he said.

Police have seized "thousands of letters" exchanged between the overground and the underground of Maoists, the police officer said.

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

"When we were confident that clear links have been established then only we moved to take action against these people, in different cities," he said.

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Information obtained after seizure of such letters and other items shows the involvement of "overground" Maoist cadres in planning subversive acts, he said.

The central committee of Maoists communicated with these activists through password protected messages sent via courier, he added.

After the Elgaar Parishad at Pune on December 31, a case was registered by police on January 8 about the event where hate speeches were delivered, he said. Most of them (who allegedly delivered the hate speeches) were associated with Kabir Kala Manch, he said.

"Our investigation revealed that a big conspiracy was being plotted by Maoist organisations and the accused were helping them to take their goals forward," Singh said.

Searches were carried out on Tuesday at the residences of prominent Telugu poet Varavara Rao in Hyderabad, activists Vernon Gonzalves and Arun Farreira in Mumbai, trade union activist Sudha Bhardwaj in Faridabad and civil liberties activist Gautam Navalakha in New Delhi, following which the five activists were arrested.

Meanwhile, the Supreme Court on Wednesday ruled that the activists should be kept under house arrest until the next date of hearing on September 6.

(With inputs from PTI)