Indian Navy continues to maintain its high alert situation at seas and in coastal areas: A defence spokesman | File photo for representation

A man suspected to have links with terror outfits was on Saturday taken into custody from a Kerala court premises, while three people have been detained in Coimbatore, Tamil Nadu in connection with the reported intrusion of six Lashkar-e-Taiba (LeT) members into Tamil Nadu.

The three were taken into custody for interrogation on suspicion that they were in touch with terrorists and are being interrogated at an undisclosed place, police said in Coimbatore, as strict vigil continued in various parts of Tamil Nadu for the second day on Saturday.

In Kerala, a man suspected to have links with terror outfits was taken into custody by police from the premises of a court at Kochi, sources said.

Malayalam Televison news channels aired video of the man being whisked away by police from the district court premises.

Police did not answer queries by the media.

His lawyer told a channel that the man from Kodungallur in Thrissur district, who returned from Bahrain two days ago, and a woman were picked up by police as they came to the court to move a plea to "prove his innocence" before law enforcement agencies following reports that he had links with LeT members who had reportedly intruded into Tamil Nadu from neighbouring Sri Lanka.

The Indian Navy has sounded a high alert at sea following intelligence inputs about the intrusion.

"... the Indian Navy continues to maintain its high alert situation at seas and in coastal areas," a defence spokesman told PTI in Kochi, Kerala.

Security was tightened in Tamil Nadu on Friday following reports that six LeT members had infiltrated the state by sea from Sri Lanka and moved to different cities including Coimbatore.

Coimbatore Police Commissioner Sumit Sharan had on Friday said the city was under a high alert following information that the terrorists were heading there.

Police said on Saturday that vehicle checks were intensified on arterial roads and highways connecting Coimbatore city with neighbouring states, and baggage thoroughly checked by armed police personnel.

Similarly checks were on in railway stations, bus stands and the airport, they said.

The Tamil Nadu commando force carried out a flag march at Mettupalayam, about 35 km from Coimbatore, to instil confidence in people about security.

Armed forces were deployed at temples, mosques and churches, which were normally targeted by terrorists as was done in Sri Lanka recently, police sources said.

A Madurai report said coastal area security had been already tightened and the Indian navy and coastguard were closely monitoring the Gulf of Mannar and Palk strait.

Security was also tightened at Madurai airport.

Tight security would be in place till August 31, police said, adding that visitors would not be allowed into the airport till then.

Kerala DGP Loknath Behera had on Friday directed district police chiefs to keep utmost vigil across the state.