Security was tightened in and around the Secretariat complex in Thiruvananthapuram, following a bomb threat.

A letter written in English, stating that an explosion would occur in front of the secretariat as a mark of protest against the recent arrest of a Hizbul Muhahideen activist, was received at the district collectorate office.

The letter attributed itself to Hizbul Mujahideen, Kerala [Images] chapter, the police said, adding the police was probing the source of the letter.

All visitors to the secretariat are being allowed in only after being frisked and metal detators have also been installed in important points. Of the four gates to the secretriat, only one gate was opened.

The anti-sabotage wing of the police conducted a search in the secretariat to search for any explosive material, but did not find anything. However, vigil would be maintained and search for explosives would continue until further orders, police sources said.

Altaf Ahamad Khan, a Kashmiri youth working in a handicraft shop was arrested from Kumali in Idukki district on January 4, for suspected terrorist links. He is now in police custody.

Khan was taken into custody on the basis of information received from Jammu and Kashmir [Images] police in connectioin with the verification of an application for a passport made by him a few months ago.