COLOMBO  - Thousands of people have been forced to flee their homes in northern Sri Lanka, joining thousands of others displaced by a government push into Tamil rebel-held territory, the UN said Monday. The United Nation's Inter-Agency Standing Committee said they expected more people to flee the ongoing fighting, with security forces attempting to take the Tamil Tigers' political capital of Kilinochchi and key base of Mullaittivu. "The general security situation in Kilinochchi and Mullaittivu districts remains volatile with ongoing military operations and advancing of the army," the UN said. Aid agencies operating inside rebel-held areas of the island's north reported that nearly 12,000 more people fled to government-controlled areas last week, in addition to the tens of thousands who have already fled. Last week, aid agencies said 112,000 people have been displaced in the past two months in the troubled areas and warned the figure could rise to 200,000 in the coming weeks. The island's defence ministry meanwhile said 22 Tamil Tiger rebels and eight soldiers were killed in the latest fighting on Sunday across the Weli Oya, Vavuniya, Kilinochchi and Mullaittivu areas. This figures raise to 5,934 the number of rebels the government claims it has killed since January, when it pulled out of a Norwegian-brokered truce. The ministry has acknowledged the loss of 553 of its own soldiers in the same period. The Liberation Tigers of Tamil Eelam (LTTE) did not comment on the claims, and reporters are barred from travelling to front line and rebel-held areas " making independent verification of the casualty claims almost impossible. Tens of thousands have died on both sides since the LTTE launched an armed struggle in 1972 to carve out a separate state for minority Tamils in the island's north and east.