The Income-tax department on Wednesday conducted a survey operation against Delhi-based think tank Centre for Policy Research (CPR), official sources said.

The premises of the think tank located near Malcha Marg in central Delhi are being covered, they said.

The search and seizure operations linked to investigations into funding of more than 20 registered but non-recognised political parties.

According to sources quoted by a television news channel, Wednesday's raids at the independent thinktank were connected to "simultaneous raids in Haryana, Maharashtra and Gujarat, among other places".

CPR, once headed by Pratap Bhanu Mehta, a vociferous critic of the BJP government, is yet to yet respond or issue. a statement on the income tax raids.

The CPR governing board is currently chaired by Meenakshi Gopinath, a political scientist associated with Jawaharlal Nehru University. She was also a principal of Lady Shri Ram College in New Delhi. The president and chief executive is Yamini Aiyar. Among the members of the board are former foreign secretary Shyam Saran and IIM professor Rama Bijapurkar.

As per its website, CPR has been recognised as a not-for-profit society by the Government of India. All contributions to it are, therefore, tax-exempt. "CPR receives grants from a variety of domestic and international sources, including foundations, corporate philanthropy, governments, and multilateral agencies," it says, adding that "a full accounting of annual finances and grants" is available on the website.

Established in 1973, CPR describes itself as "a non-partisan, independent institution dedicated to conducting research that contributes to high quality scholarship, better policies, and a more robust public discourse about the issues that impact life in India".

"Asking the relevant questions" is one of its stated goals.