An alert has been sounded in Gujarat and all metros by central security agencies following reports that 10 terrorists suspected to be from Pakistan have entered the western state to carry out attacks against high-value targets.

Security was on Sunday intensified across Gujarat, which cancelled leave of all police personnel. Two NSG teams comprising nearly 200 personnel have been sent to Ahmedabad from Delhi.

Advisory has been issued to enhance security at all strategic locations, sensitive industrial sites and religious places after intelligence inputs suggested that the terrorists have entered Gujarat taking the sea route, official sources said.

A Pakistani fishing boat was seized by a BSF patrol party on Friday after its occupants fled upon seeing the security personnel in the Koteshwar creek area off the Kutch coast along the Indo-Pakistan border, heightening the security concerns.

As Shivratri falls on Monday, security has been ramped up at major religious sites in Gujarat like Somnath Temple and Akshardham and in metro cities — Mumbai, Delhi, Chennai, Kolkata and Bengaluru, the sources said.

Vital installations across the state like railway stations and airports are being secured.

In view of the January 2 terror attack in Pathankot airbase, security agencies were not taking any chances and all possible steps are being directed to prevent any possible terror attacks, they said.

Gujarat DGP P C Thakur said combing operations have started across various locations. Policemen were seen patrolling the highways since early this morning.

Thakur issued orders late last night cancelling leave of all officers and personnel and said they were prepared to deal with any situation.

"We are on high alert and prepared to deal any situation.

We have started combing operations across various locations.

We have also sensitised places that see high rate of footfall," he said.

High level meetings, headed by state Home Secretary P K Taneja, were held in Gandhinagar early this morning and late last night.

In Kolkata, security has been stepped up at NSC Bose International Airport after an email threat that it would be blown up within 24 hours, airport officials said.

The e-mail came in the airport manager’s ID early on Sunday and it was claimed to have been sent from Germany, officials said.

The cyber crime team of the airport is probing the matter.

Luggages and cars of passengers are being throughly checked while various parts of the airport are being scanned, officials said.