Satellite images show clearance of camps for displaced people in Sri Lanka's conflict zone.
Violence has continued unabated in Sri Lanka's Tamil war zone, where more than 50 people died when the main hospital was shelled for a second day.
While the army cast doubt on the new attack, a doctor in Mullaitivu said it had hit people injured during earlier shelling which claimed nearly 50 lives.
A local Red Cross employee was also killed as violence raged.
Satellite images have emerged which appear to show recent heavy shelling in the government-designated "safe zone".
Images released by Human Rights Watch show crater marks and considerable population displacement between 6 and 10 May.
The organisation says it has also gathered witness testimony contradicting army assertions that they are not using heavy weaponry.
Sri Lanka has accused the Tamil Tiger rebels of being behind recent attacks using heavy weapons.
The UN estimates that about 50,000 civilians are trapped by the conflict, in a three-sq-km strip of land.
'Shelter hit'
A day after Britain and the US called on both the government and the rebels to end hostilities immediately there is no sign of that happening, the BBC's Charles Haviland reports from Colombo.
See a map of the conflict region
A Sri Lankan technician for the International Committee of the Red Cross, a 31-year-old father, was killed in shelling along with his mother.
International aid agencies are unable to enter the "safe area"
There are accounts of dozens more civilians also being killed.
Dr T Varatharajah told the BBC more than 50 people had died when two shells hit the zone's main hospital compound.
Sources in the UN said they agreed with that figure and that 100 had been injured.
Shelling of the same hospital on Monday night and Tuesday morning left 49 dead and 86 injured, the doctor told the BBC earlier.
A rebel spokesman said a home for mentally disabled women was also shelled, resulting in the death of 38 people.
He blamed the government side but the Sri Lankan military spokesman, Brig Udaya Nanayakkara, said the rebels were spreading false propaganda.
The army was, he said, using only small arms during its military advance and there was, he added, no facility for handicapped people nearby.
Asked about recent video from Tamil sources, purporting to show the aftermath of hospital shellings, he said the Tigers were booby-trapping all sorts of facilities and people might be caught in that.
The government says it is in the final stages of wiping out the Tamil Tigers but the rebels have said they will not surrender.
Amnesty International has demanded "immediate and unhindered" access to the war zone for international monitors and humanitarian agencies.
Accusing both sides of putting civilians' lives in danger, it urged the UN Security Council to create a commission to investigate "serious violations by all parties in recent months".
Sri Lanka has accused the Tamil Tiger rebels of being behind recent attacks using heavy weapons.
The UN estimates that about 50,000 civilians are trapped by the conflict, in a three-sq-km strip of land.
'Shelter hit'
A day after Britain and the US called on both the government and the rebels to end hostilities immediately there is no sign of that happening, the BBC's Charles Haviland reports from Colombo.
See a map of the conflict region
A Sri Lankan technician for the International Committee of the Red Cross, a 31-year-old father, was killed in shelling along with his mother.
International aid agencies are unable to enter the "safe area"
There are accounts of dozens more civilians also being killed.
Dr T Varatharajah told the BBC more than 50 people had died when two shells hit the zone's main hospital compound.
Sources in the UN said they agreed with that figure and that 100 had been injured.
Shelling of the same hospital on Monday night and Tuesday morning left 49 dead and 86 injured, the doctor told the BBC earlier.
A rebel spokesman said a home for mentally disabled women was also shelled, resulting in the death of 38 people.
He blamed the government side but the Sri Lankan military spokesman, Brig Udaya Nanayakkara, said the rebels were spreading false propaganda.
The army was, he said, using only small arms during its military advance and there was, he added, no facility for handicapped people nearby.
Asked about recent video from Tamil sources, purporting to show the aftermath of hospital shellings, he said the Tigers were booby-trapping all sorts of facilities and people might be caught in that.
The government says it is in the final stages of wiping out the Tamil Tigers but the rebels have said they will not surrender.
Amnesty International has demanded "immediate and unhindered" access to the war zone for international monitors and humanitarian agencies.
Accusing both sides of putting civilians' lives in danger, it urged the UN Security Council to create a commission to investigate "serious violations by all parties in recent months".