NEW DELHI (AFP) - Indian police on Monday (June 27) arrested the co-founder of a top fact-checking website who has been a vocal critic of Prime Minister Narendra Modi's government, his colleague said.

Mr Mohammed Zubair was arrested in Delhi after being called in for questioning in an earlier case, said Mr Pratik Sinha, who runs the Alt-News web site together with Mr Zubair.

Mr Sinha said in a post on Twitter that his colleague was arrested illegally and without warning and was being held by police in Delhi.

Mr Zubair has been one of the fiercest critics of Mr Modi's ruling Hindu nationalist Bharatiya Janata Party (BJP) and has frequently called out hate speech by Hindu fringe groups on the Internet.

He has faced several legal cases over the years which his supporters dismiss as politically motivated attempts to silence a critic.

Some local media reports linked Mr Zubair's arrest Monday to the recent controversy over incendiary remarks about Prophet Mohammed made by a BJP spokesperson, which sparked widespread global protests and outrage from the Islamic world.

Many Hindu nationalists in the last few weeks have drawn attention to past comments on social media made by Mr Zubair and other Mr Modi critics and demanded that he be prosecuted for hurting their religious feelings.

Most government critics however see Mr Zubair's arrest as part of a crackdown on free-speech and rights activists that India has seen since Mr Modi's ascent to power in May 2014.

On Saturday, police detained activist Teesta Setalvad who hails from Mr Modi's western home state of Gujarat.

Ms Setalvad has been campaigning to have Mr Modi declared complicit in deadly sectarian riots 20 years ago.

Protests were held in several Indian cities on Monday with rights activists and free-speech organisations demanding Ms Setalvad's release and describing her detention as "politics of vengeance".