The historic Red Fort complex has been temporarily closed for visitors due to security reasons, a senior ASI official said Tuesday, amid a massive deployment of police and paramilitary forces in central Delhi in view of the farmers' march.

The iconic Mughal-era monument, a UNESCO World Heritage Site in old Delhi, was "suddenly sealed" late Monday night "due to security reasons", the official said. Heavy security has been deployed there since late last night.

"The Red Fort complex has been closed for visitors," the official told PTI. Asked when will the 17th-century monument will reopen, the senior official said, "it will be the call of security agencies".

Security in Delhi has been intensified with multi-layer barricades, concrete blocks, iron nails and walls of containers at border points to stop a 'Delhi Chalo' march of farmers from entering the national capital on Tuesday, after talks between farm leaders and the Centre remained inconclusive.