The Sri Lankan Air Force has increased air strikes and spy plane activity over Tamil Tiger rebel-held areas in the north, says European truce monitors on Monday.
Combat seems to have "shifted from the east to the areas closer to Kilinochchi, the main rebel-held town in the north," says The Sri Lanka Monitoring Mission in its weekly media statement.
Kilinochchi is the main rebel-held town in the north. The statement said there were up to eight air strikes in northern rebel-held areas in the week of April 23-29.
"Half the air strikes have taken place within eight kilometers (five miles) from Kilinochchi town, and one as close as three kilometers (two miles) from the SLMM (Sri Lanka Monitoring Mission) office," the statement says.
It said the number of unmanned aircraft and spy planes flying over the north had also increased.
In 2002, Norway brokered a government-rebel truce that officially remains in place, although the fighting has worsened. Both sides insist they respect the cease-fire, and are only fighting in response to the other's aggression.
The government has already ousted insurgents from bases in eastern Sri Lanka, and officials say they plan to make a push so on into the rebels' heartland in the north, where they run a mini-state complete with border guards, schools and traffic police. In the latest round of intense fighting at least 32 rebels and four government soldiers have been killed in a series of gunbattles, a naval battle and a land mine blast this week.
The Tamil Tigers have fought government troops since 1983 for an independent homeland in the north and east for Sri Lanka's minority ethnic Tamils after decades of discrimination by the majority Sinhalese.
The conflict killed at least 65,000 people before the 2002 cease-fire. Air raids, bus bombings, suicide attacks and jungle clashes have left an estimated 4,000 more dead since December 2005.