Mumbai: Pune police launched raids in five states at dawn on Tuesday, picking up mostly Left-leaning activists and lawyers and igniting outrage in civil society that described the crackdown as "absolutely chilling".

The five persons arrested are poet and Left-wing activist Varavara Rao; rights activists Vernon Gonzalves and Arun Ferreira; lawyer, trade unionist and tribal rights activist Sudha Bharadwaj and civil liberties activist Gautam Navlakha.

The near-simultaneous clampdown rolled at 6am in Mumbai, Delhi, Ranchi, Goa and Hyderabad.

Pro-government media celebrated the raids as an offensive on "urban Naxals". Those arrested have been charged under Indian Penal Code sections that deal with promotion of enmity between different groups on grounds of religion, race, place of birth, residence, language and committing acts prejudicial to maintenance of harmony. The stringent Unlawful Activities (Prevention) Act, too, has been applied.

Raids were also carried out on the residences of 80-year-old tribal rights activist Stan Swamy in Ranchi, lawyer Susan Abraham in Mumbai's Andheri, Rao's daughter Pavana and her husband and Dalit activist K. Satyanarayana, Rao's other daughter Anala and her husband and senior journalist K.V. Kurmanath, and journalist Kranti Tekula.

In Goa, a Pune police team raided the house of a writer and professor in the Goa Institute of Management, Anand Teltumbde.

Historian and columnist Ramachandra Guha called the action "absolutely chilling". 

Author Arundhati Roy told PTI the arrests were "a dangerous sign of a government that fears it is losing its mandate and is falling into panic. That lawyers, poets, writers, Dalit rights activists and intellectuals are being arrested on ludicrous charges... tells us very clearly where India is headed".

Congress leader Rahul Gandhi tweeted: "There is only place for one NGO in India and it's called the RSS. Shut down all other NGOs."

Sources said the official reason for the crackdown was the eight-month-old Bhima-Koregaon case in which one person was killed in clashes between the disadvantaged sections and the upper castes during an annual event to commemorate a battle in which Dalit soldiers defeated the Brahmin Peshwa rulers in 1818.

During the course of the investigation, the police had claimed that they had stumbled on a Maoist letter that spoke of a "Rajiv Gandhi-type incident" against Prime Minister Narendra Modi during one of his road shows.

The claim had prompted calls for tough action, and central minister Arun Jaitley had targeted "half-Maoists", tweeting that "willingly or otherwise, they become over-ground face of the underground".

On Tuesday, Shivaji Bhodke, joint commissioner of police, Pune, said: "The operation has been based on evidence gathered from investigations in the case. More arrests are likely."

The arrests coincided with renewed glare on pro-Hindutva extremists allegedly linked to the murder of rationalist Narendra Dabholkar.

Tuesday's crackdown stands in contrast with the police's reluctance to arrest Sambhaji Bhide, a suspect in the Bhima-Koregaon case, named by a Dalit leader. Bhide, the Shiv Pratishthan founder president, was once addressed by the Prime Minister as "Guruji".