The ICRC is one of the few aid agencies still operating in the war zone
The International Committee of the Red Cross (ICRC) says that one of its employees has been killed in a shell attack in Sri Lanka's war zone.
The victim - a Sri Lankan working as a water technician - was killed along with his mother.
He was working in the small pocket of territory still controlled by Tamil rebels where fighting is taking place.
The dead man - who was married with a child - is the third ICRC employee to be killed in the zone in recent weeks.
The ICRC has more than 20 employees there.
Correspondents say that it is not clear who carried out the attack.
On Tuesday the ICRC said that heavy clashes had prevented its ship from landing and evacuating sick and wounded people from the war zone and made a plea for better access.
There are also unconfirmed reports that a hospital in the fighting zone has been hit by shelling, with more than a dozen deaths.
A doctor in the area told the AFP news agency that three shells hit the make-shift hospital.
In another development, the military said it had repulsed a wave of rebel suicide boat strikes against army positions along the north-eastern coast.
There has been no comment on this from the rebels.
Reports from the war zone cannot by verified as no independent journalists are allowed.
The escalation in fighting comes amid increasing international calls for a temporary ceasefire to allow thousands of trapped civilians to leave the conflict zone.
The US and UK have urged both the government and the Tamil Tigers to stop fighting "immediately" and allow an evacuation.
US Secretary of State Hillary Clinton and her UK counterpart David Miliband expressed alarm at the large number of reported civilian casualties.
And the top UN aid official said the situation in the conflict zone was "awful".
The Sri Lankan government has consistently denied allegations that the army has caused civilian casualties or used heavy weapons in civilian areas.
The UN estimates that about 50,000 civilians are trapped by the conflict, in a three-sq-km strip of land.