New Delhi, Aug 11 - The home ministry has warned the police in three cities to raise their levels of preparedness to face up to any terror attack in the runup to Independence Day Saturday.

Senior ministry officials told IANS that advisories had been sent to the police forces of New Delhi, Kolkata and Hyderabad to be alert, indicating that intelligence inputs had warned of possible attacks.

The home ministry has asked the police to strengthen security in market places, cinema halls, bus and railway stations and iconic buildings in the three cities.

Meanwhile the US government, in a fresh security alert to its citizens in India, has also warned of possible terrorist attacks in the country.

A message issued last week asked American nationals in India to 'maintain a heightened situational awareness and a low profile'.