Navi Mumbai resident Zuber Ahmed Khan, who recently posted on Facebook that he wanted to join Isis and surrender his Indian citizenship, was detained in Delhi on Friday.
Khan, a journalist, had also called 1993 Mumbai blasts convict Yakub Memon a martyr.
Zuber Khan had said that he wanted to surrender his Indian passport and join the Islamic State "as a spokesperson for foreign affairs or a government journalist".
He had shared his plans of how he wanted to travel to Delhi and visit the Iraqi embassy to submit his "memorandum to Caliphate Baghdadi".
He was arrested from near the Iraq embassy in Delhi, after the embassy alerted the Delhi police of a man speaking about Isis, according to The Hindu. The newspaper cited sources claiming that Khan may be 'mentally unstable'.
Khan claims to be the editor of a newspaper 'Journalist for International Peace'.
He had also written a blog post addressed to Isis leader Abu Bakr al-Baghdadi about why he wanted to join Isis.
"I am fighting for the rights of Muslims using my own money. I will be the voice of Muslims and place the true picture of Muslims before society... the Isis does not betray those who help it on the basis of religion," Khan had also said on his blog.
The police questioned his family and launched a manhunt for Khan. Some reports suggest that he had escaped arrest in Mumbai.
Journalist Zuber Khan from Navi Mumbai arested in Delhi after supporting ISIS on Facebook.
— Times of India (@timesofindia) August 7, 2015