There has been a powerful bomb attack on a Sri Lankan military convoy in the north of the island, officials say. Police fear many casualties.
At least 67 people have been killed in a suicide attack on a navy convoy in northern Sri Lanka, the military says.
It comes shortly after Japan's peace envoy to Sri Lanka met President Mahinda Rajapakse in Colombo.
Military officials told the BBC that they had counted the bodies near the town of Digampathana, near Trincomalee.
It was the first of a number of new diplomatic efforts ahead of talks due between the government and the Tamil Tigers at the end of October.
They say that at least 60 people - navy personnel and civilians - were injured in a "huge explosion" involving an "explosive-laden vehicle".
At least 2,000 people are estimated to have been killed in violence this year.
The blasts come amid renewed violence in Sri Lanka, with both the military and Tamil rebels taking heavy losses.
Norway's envoy, Jon Hanssen-Bauer is due on the island on Tuesday. Richard Boucher, the US Assistant Secretary of State is due on Thursday.
The diplomats will be hoping to help the government and the Tamil Tigers rebels reconcile their differences.
No details of the meeting between the Japanese envoy, Yasushi Akashi and Mr Rajapakse have been released. Mr Akashi is due to meet senior Tamil Tigers in the north of the island later in the week.
Japan is one of the key international donors to Sri Lanka.
Threat to talks
There were more reports of violence over the weekend.
The military said the navy destroyed a trawler carrying arms of the island's west coast on Sunday, leaving at least five rebels dead.
The pro-Tamil Tiger website says four civilians were killed in the northern Jaffna peninsula in three separate incidents. In each case it says the shootings were carried out by unidentified gunmen.
At least three Sinhala civilians were reported to have been kidnapped and killed near the town of Vavuniya, 260 kms (160 miles) north of the capital, Colombo.
Correspondents say the violence could derail the peace talks which are due to take place in Geneva, Switzerland.
