The United Nations is evacuating civilians wounded in fighting between Sri Lankan government forces and Tamil Tiger fighters in the north of the country.
International aid agencies have warned of a major humanitarian crisis in the country, with hundreds of civilians killed in the past two weeks and 250,000 trapped by intense fighting.
A UN spokesman told the BBC that the convoy had passed the frontlines.
"The convoy just crossed the frontline [with] hundreds of the civilians wounded by the fighting, including 50 critically wounded children, who are being moved to a Ministry of Health hospital in Vavuniya," Gordon Weiss told the British news agency.
Earlier this week, the International Committee of the Red Cross (ICRC) appealed to government forces and separatist Tamil Tigers to respect the laws of war and allow the "safe and voluntary movement" of civilians out of combat zones.
"We are in an all-out decisive stage of the conflict," Jacques de Maio, ICRC head of operations for South Asia, told a news briefing in Geneva. "There is definitely a major humanitarian situation unfolding right now." The Sri Lankan army seized the last major town the rebels controlled, the northeastern port of Mullaittivu, on Sunday aiming to strike a death blow to the 25-year insurgency, one of the longest-running in Asia.
Intense fighting continues in the northern Vanni region, which de Maio called "the last LTTE (Liberation Tigers of Tamil Eelam) stronghold" where 250,000 civilians are trapped.
Hundreds of people have been killed in the past two weeks according to approximate figures the ICRC compiled from sources including hospitals and the Sri Lankan Red Cross.
Much of the fighting has been "intrinsically incompatible with full respect of the basic rules of the law of war," de Maio said. Embodied in the Geneva Conventions, they include the protection of civilians, precaution, distinction between civilian and military structures, and proportionality.