Sri Lanka's military says more than 700 civilians have fled to a government-controlled safe zone to escape fighting in the north.

A brief statement from the army said the civilians escaped Thursday from Tamil Tiger rebel-held territory around Mullaittivu, which has seen intense battles for several weeks.

Several senior government officials today rejected a U.S. call for talks with the Tamil Tigers and are vowing to press on with the offensive until the separatist rebel movement is crushed.

The United Nations and other relief agencies say about 250,000 civilians are trapped alongside the rebels in a 300-square-kilometer swath of jungle, and civilian casualties have been rising.

On Wednesday, U.N. officials said repeated artillery strikes forced aid workers to close the last remaining hospital inside the war zone. The International Committee of the Red Cross said it evacuated the last 300 patients, who are now sheltering in a makeshift hospital with no clean drinking water, near the northeastern coast.  

The United States, Britain and Canada urged both sides to stop fighting temporarily to allow civilians safe passage out of the conflict zone.

Sri Lanka's key international donors (the EU, U.S., Japan and Norway) called on the Tamil Tigers to surrender, in an effort to spare civilians.

Human Rights Watch issued a statement Wednesday saying Sri Lanka's government is showing a "callous indifference" toward civilians trapped in the war zone.

The government has urged civilians to move to a "safe zone" near Mullaittivu, but human rights groups have in the past said the rebels refuse to allow people to leave.

Tamil Tiger rebels have been fighting since 1983 to establish an independent homeland for Sri Lanka's Tamil minority.  More than 70,000 people have died in the conflict.

Some information for this report was provided by AFP, AP and Reuters.