The senior official told IANS that places of worship, railway stations, bus terminals and markets have been identified as places for special obeservation by police and para-military personnel Dec 6.
"The peaceful atmosphere which prevailed after the Sep 30 verdict by the Allahabad High Court verdict in the Ayodhya title suit case has been encouraging. But the central government wants the states not to lower their guard on the day," he added.
Reports from Uttar Pradesh said that high security is in place in the twin-cities of Ayodhya and Faizabad.
Security has been put on top gear in Varanasi and Mathura - two other religiously important places having disputed places of worship - and sensitive districts including Aligarh, Lucknow, Bareilly, Gorakhpur, Moradabad, Meerut and Kanpur.
A large number of police personnel, Provincial Armed Constabulary (PAC) and Rapid Action Force (RAF) would be deployed to ensure security, state officials said.
The home ministry official said several other communally sensitive states including Gujarat, Maharashtra, Rajasthan and all the southern states have specially alerted. Jammu and Kashmir would be also under high alert.
Cities like Ahmedabad, Surat (Gujarat), Mumbai, Bhiwandi (Maharashtra), Hyderabad, Coimbatore (Tamil Nadu), Bangalore and Kozhikode (Kerala), which have a history of communal clashes or activities of radical religious organisations would be under special watch, the official added.
The Delhi Police Sunday said the security arrangements in the capital ahead of the 18th anniversary of the Babri Masjid's demolition Monday were "routine".
"The security arrangements are routine and we will keep a vigil on the significant spots in the capital," Delhi Police spokesman Rajan Bhagat told IANS.
According to police, the sensitive and significant spots in the city are already under security cover and no "extraordinary" measures are required.
A mob of radical Hindus demolished the 16th century Babri mosque Dec 6, 1992, alleging that it was built after razing a temple built on the birthplace of Hindu deity Ram.
On Sep 30 this year, a three-judge special bench Allahabad High Court ruled that the spot in Ayodhya where a makeshift temple was built hastily after razing the mosque was the spot where Ram was born.
It had ordered division of the disputed 90 ft by 120 ft piece of land where the Babri Masjid once stood into three parts - one to Ram Lalla deity, one to the Nirmohi Akhara and one to the Sunni Wakf Board.
Dissatisfied with the judgment, both Hindu and Muslim groups have filed appeals in the Supreme Court.