The US-based Sikhs for Justice (SFJ) is a pro-Khalistan group.
"Sikhs For Justice (SFJ), an unlawful organisation under the UAPA, 1967, launched a campaign for registering supporters for its cause. On recommendation of MHA, MEITY has issued orders under Sec. 69 A of the I.T. Act, 2000, for blocking 40 websites of SFJ," a home ministry spokesperson said.
The Ministry of Electronics and Information Technology (MEITY) is the nodal authority for monitoring the cyber space in India.
Last year, the home ministry had banned the SFJ for its alleged anti-national activities.
The SFJ had pushed for Sikh Referendum 2020 as part of its separatist agenda.
It openly espouses the cause of Khalistan and in that process challenges the sovereignty and territorial integrity of India, another official said.
On July 1, the home ministry had declared nine individuals linked to separatist Khalistani outfits, including four based in Pakistan, as designated terrorists under the provisions of Unlawful Activities (Prevention) Act (UAPA).
The individuals belonged to various terrorist organisations.
Among them were Wadhawa Singh Babbar, chief of Babbar Khalsa International (BKI); Lakhbir Singh, who heads International Sikh Youth Federation; Ranjeet Singh, chief of Khalistan Zindabad Force (KZB) and Paramjit Singh, who leads Khalistan Commando Force. All these four are Pakistan-based.
The home ministry had said these nine individuals were operating from Pakistan and other foreign soil and were involved in various acts of terrorism.
"They have been relentless in their nefarious efforts of destabilising the country, by trying to revive militancy in Punjab through their anti-national activities and through their support to and involvement in the Khalistan movement," it had said.