The army has received inputs that there may be a terror attack in southern part of India, a top army commander said on Monday.
Some abandoned boats have been recovered in the Sir Creek area, Lt Gen S K Saini, GOC-in-C of the Army's Southern Command, told reporters at an event near Pune.
"We have got many inputs that there may be a terrorist attack in southern part of India and the peninsular India," he said.
The army has taken measures in the Sir Creek region, keeping in mind the enhanced threat perception, he said.
Kerala police chief Lokanath Behera, meanwhile, asked all district police heads to maintain high alert across the state.
The Director General of Police directed personnel to maintain heightened vigil at bus stands, railway stations, airports and places where people gather in large numbers.
"Security will be tightened at all places where people come out in huge numbers to celebrate Onam," a police release said.
A defence spokesperson in Chennai said the "northern most point of the Army's southern command includes some parts of Gujarat also. The word south from southern command GOC does not mean Tamil Nadu, Kerala, Andhra Pradesh and Karnataka only. It includes complete southern peninsula and parts of Gujarat."
In Andhra Pradesh, security along the 974 km long coastline has been beefed up following threats of a possible terror attack in south India, a top police official said.
"Security has also been stepped up at vital installations in the state by deploying the AP Special Protection Force," Additional Director General of Police (Law and Order) Ravi Shankar Ayyanar said.
"Our control room is in constant touch 24x7 with all the coastal police stations, as well as the SPF personnel at vital installations and closely monitoring the situation," he added.
In particular, security has also been beefed up at Tirumala, the abode of God Venkateswara and the Satish Dhawan Space Centre at Sriharikota.