At least 10 Tamils have been killed in a mine explosion in eastern Sri Lanka, Tamil Tiger rebels and medics say.
Villagers hurt in the blast were taken to hospital in Batticaloa
The rebels told the BBC the victims were civilians and that 13 others had been hurt in the blast in rebel-held territory near the town of Batticaloa.
A rebel statement blamed the army for the blast, which the military denied.
The deaths came a day before rebels and government are to discuss security for truce monitors. Two months of violence have claimed more than 300 lives.
The blast occurred as locals were on their way to market near Vadamunai, a village about 70km (45 miles) north-west of the town of Batticaloa.
The rebels said seven of the villagers were killed instantly. Three others died later of their injuries, medics said.
Doctors travelling with an International Committee of the Red Cross (ICRC) escort evacuated some of the injured from rebel-held territory.
Dr S Dakshinamoorthy, senior health officer in Batticaloa district, told the BBC they had received nine of the injured, two of whom had later died en route to hospital.
The others were taken for treatment in Batticaloa. "Among the injured one of them is in a serious condition," he said.
A woman later died of her injuries, the hospital said.
The doctor said villagers had told him a three-month-old girl had escaped with minor injuries in the blast, but her mother had been killed.
A statement from the Liberation Tigers of Tamil Eelam (LTTE) accused troops of attacking the tractor which was taking the villagers to market.
"This is the largest attack on a civilian vehicle in the north-east since the ceasefire was signed and was clearly carried out by the Sri Lanka army in an LTTE area against civilians," the statement said.
The military, dozens of whose personnel have died in mine blasts blamed on the Tamil Tigers this year, denied its forces had been operating behind rebel lines.
"The security forces do not go into those areas," army spokesman Prasad Samarasinghe told Reuters. "We totally reject these accusations."
The government and the rebels last held direct peace talks in February, but violence swiftly resumed.
Suspected rebel attacks on security forces and killings of Tamils blamed on the army and others have soared in recent months.
Scandinavian ceasefire monitors have accused both sides of violating a truce agreed in 2002.
This week's talks in Oslo, hosted by peace broker Norway, are due to cover only the security of monitoring mission staff in Sri Lanka, not wider peace issues.
Observers do not expect any breakthrough, but say the fact the two sides are meeting is a positive move.