Guwahati, Jan 25 (Agencies): In view of the boycott call of the Republic Day celebration given by ULFA with five other militant groups, the State Government has tightened security throughout Assam to prevent any untoward incidents.

Patrolling has been intensified in the districts where militants are more active and additional security posts have been posted in areas in and around vital installations of the state, official sources said on Tuesday.

Securities in railway stations and railway tracks have been beefed up even as night running of trains to and from the state has been suspended from the night of January 23.

Security in and around bus terminus, airports, refineries, oil pipelines and other major industrial units have also been tightened. Entry and exit of vehicles in all the vulnerable districts of both upper and lower Assam are being closely monitored with all vehicles being checked.

Army helicopters are making aerial surveys of parade grounds where official functions are scheduled to take place in all parts of the districts.

River patrolling has also been intensified to check the movement of suspicious persons.

The ULFA, led by its Commander in Chief Paresh Barua, had recently warned that it would strike if the government did not stop the alleged killings of ''innocent indigenous Assamese people''.

The outfit also joined other militant organisations of the North East in calling for a boycott of Republic Day celebrations and a general strike from one am to 5.30 pm on Wednesday.