"Over the last several months, acts of terrorism including bombings and political assassinations have occurred in Sri Lanka," the State Department said in a statement.
"The Liberation Tigers of Tamil Elam (LTTE) and Sri Lankan military forces have clashed on several occasions, and this fighting has escalated in recent weeks," the department said.
"While most of the country remains largely unaffected, the department warns Americans against travelling to areas in the North and East of the country given the dangers caused by the ongoing fighting between LTTE, other armed groups, and Sri Lankan military forces," it said.
The State Department also alerted Americans to the dangers posed by recent acts of terrorism throughout Sri Lanka.
It expressed particular concern about the areas of the north and east, defined as the regions north of a line following the highway from Puttalam through Anuradhapura to Trincomalee, and east down to Batticaloa.
"Travel to these areas and into any LTTE-controlled territory may pose severe hazards," the department said.
"US government personnel are generally prohibited from travelling in these areas, and American citizens residing in these areas should depart immediately as their safety cannot be effectively guaranteed."
The travel warning was set to expire on April 19, 2007.

Copyright AFP (Agence France-Presse), 2006