Sudha Bharadwaj was among the five activists arrested over allegations of Maoist links.
The Pune police claimed on Saturday that all the seven organisations, to which some of the left-wing activists arrested recently for alleged Maoist links belonged, were fronts of the banned CPI (Maoist).
The police have arrested 10 activists during the probe into alleged Maoist connection behind the Elgar Parishad conclave held in Pune in December last year.
According to a media report published on Saturday, only one of the outfits to which eight of the arrested activists belonged was declared as unlawful.
A senior Pune police official, however, said all the seven outfits were "formations and front organisations" of the Communist Party of India (Maoist), banned in 2009.
The ban on the CPI (Maoist) covered all its offshoots, Pune Joint Commissioner of Police Shivajirao Bodkhe said, citing the Union government's gazette of June 22, 2009.
"The Central Government hereby makes an order so as to add that the Communist Party of India (Maoist) and all its formations and front organisations as terrorist organisations," the gazette said.
According to the police, arrested Telugu poet Varavara Rao is allegedly connected with the Revolutionary Democratic Front (RDF), which has been declared unlawful in Andhra Pradesh, Odisha and Telangana for allegedly being a front of the CPI (Maoist).
Besides, Gautam Navlakha is allegedly connected with the People's Union for Democratic Rights (PUDR) and Sudha Bharadwaj and Surendra Gadling with the Indian Association of People's Lawyers.
Rona Wilson is allegedly connected with the Committee for the Release of Political Prisoners, Shoma Sen with the Committee for Protection of Democratic Rights, Sudhir Dhawale with the Republican Panthers and Mahesh Raut with the Visthapan Virodhi Jan Vikas Andolan.
Vernon Gonsalves and Arun Ferreira are allegedly associated with the Maharashtra State Committee of the CPI (Maoist), the police have said.
Varavara Rao, Gautam Navlakha, Sudha Bharadwaj, Vernon Gonsalves and Arun Ferreira were arrested last month, while the five others were arrested in June.
Following the arrest of the five activists last month, the Supreme Court had ordered to keep them under house arrest on a petition challenging the police action.