Pakistan high commissioner Shahid Malik received a letter last week carrying a threat to his life following which security for him and the mission was increased.

A request for enhancement of security was received from the Pakistan high commission six days back after which necessary action was taken, official sources said.

The letter dated January 18, purportedly written by a group claiming to be All India Anti-terrorism Group, asked the Pakistan high commissioner to leave the country within three days.

While the security agencies claimed that the letter was prank played by somebody, security around the Mission as well as the residence of Malik was enhanced "considerably", the sources said.

An additional vehicle carrying security personnel has been provided for his safety, the sources said.

When contacted, acting high commissioner Rifat Masood said all necessary action had been taken by the Indian Government following the threat.