Officials said the Intelligence Bureau had tipped of Uttar Pradesh Police on "certain threat perceptions" which were "attended to immediately".
"We are in a state of high alert. Uttar Pradesh has been on terror hit list and there have been many incidents in the past and all precautions are being taken," a police officer told IANS.
State capital Lucknow and other sensitive places like Agra, Kanpur, Allahabad, Varanasi, Mathura, Bareilly and Aligarh were put on high alert, while ani-terror squad (ATS) commandoes were deployed in Noida and Ghaziabad.
Additional Director General of Police Daljit Singh told IANS that the local intelligence units has also been sensitised about the possible threats.
Police were keeping an eye on railway stations, bus stations and all public places, he said.
Special vigil was also being maintained along India-Nepal border.