In Bangladesh's north-eastern Sylhet district security was stepped up after a car carrying the Jute Minister, Hannan Shah, was attacked by Islamic activists demanding the death of Nasreen.
The United News of Bangladesh news agency did not identify the ambassador said to be harbouring the author, but quoted an unidentified source saying the envoy violated the Vienna Convention on diplomatic norms by giving 'undue protection to a person accused under the law of an independent and sovereign country'.
'The envoy should be declared persona non grata for interference in the internal affairs of a sovereign country,' the source said.
Nasreen, the target of an Islamic fundamentalist campaign to introduce anti-blasphemy laws, has denied blaspheming the Koran. She gained prominence after the Dhaka government banned her book Lajja or 'Shame' saying it was blasphemous and offended Islamic sentiment.
Two radical groups have put a dollars 3,750 ( pounds 2,500) bounty on her head. The United States, Norway and Unesco have called for her protection.
Police have repeatedly said they had so far failed to track her down, but rumours in Dhaka pointed at Western missions as her only possible hideout. If tracked down and found guilty, Nasreen faces two years hard labour.
One person was killed and 300 injured on Thursday in clashes between secular groups and Islamic fundamentalists who had organised a nationwide general strike to demand her punishment. - AFP