Security was beefed-up around churches and at metro stations in the national capital in the wake of the Kerala convention centre blast on Sunday.

A senior police officer, who requested anonymity, said security has been tightened across the city's main markets, churches, metro stations, bus stands, railway stations, and other public places.

"Teams have been informed to put barricades across the border area from Uttar Pradesh Side and Haryana side. Police in civil dress, riders and PCRs have been asked to stay on alert and not to ignore any information they receive," the officer said.

"We are already keeping strict vigil in overcrowded markets. Extra platoon deployment has already been done considering the festival season," the person said.

On Sunday, a blast ripped through a convention centre in Kerala's Kalamassery, killing a woman and wounding 36 others.

The blast occurred during the convention of the Jehovah's Witnesses -- a Christian religious group that originated in the United States of America in the 19th century.

According to sources, the Special Cell of Delhi Police is in continuous touch with central agencies.

On October 2, the Special Cell of the Delhi Police arrested one of NIA's most wanted terrorists, Mohammad Shahnawaz Alam, and his two associates, who were part of an ISI-sponsored module "disguised" as an ISIS module and seized incriminating material, including those suspected to be used in IED fabrication.

The anti-terror agency had placed a reward of Rs 3 lakh on any information leading to arrest of Shahnawaz.

An engineer by profession, Shahnawaz had escaped from Pune Police custody and was living in Delhi at the time of his arrest. His two associates were identified as Imran and Yunus.

During investigation, it came to light that he and his associates were planning a terror strike.

"We have been on alert since Shahnawaz, Imran, and Yunus were arrested. Strict vigil and round-the-clock patrolling is being carried out on a daily basis," the officer said.

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