Of at least 10 people killed across the country, a child, another civilian and three armed militants died when regime troops opened fire with machineguns in the flashpoint town of Khan Sheikhun, the scene of yesterday's blast, the Syrian Observatory for Human Rights said.
Four other people died of wounds suffered yesterday when regime troops "massacred" 20 people during a funeral procession in the town, according to the Britain-based group.
During the funeral, a convoy of UN truce observers was struck by a homemade bomb, damaging three vehicles but causing no casualties, the United Nations said.
Six members of the team were forced to spend the night with activists in Khan Sheikhun, a town in the northwestern province of Idlib that has been under regime shelling, an activist said.
"The monitors had to stay behind after their car was damaged by the blast," said activist Abu Hammam.
The monitors were safe and evacuated on Wednesday afternoon, after having witnessed "death with their own eyes" during the funeral procession, Abu Hammam told the news agency by telephone.
The blast came as the observers made their way in a convoy of vehicles along a narrow street in Khan Sheikhun, said activists, rebels and the watchdog.
It was the second roadside bombing involving the observers' vehicles in less than a week, after a convoy in the flashpoint southern city of Daraa wounded six Syrian soldiers on May 9.
The United Nations, which accuses both sides of violating an April 12 ceasefire, reaffirmed its condemnation of any violence against the monitors.
"This mission is there to help the people of Syria, to help ensure that the six-point plan is implemented," spokesman Martin Nesirky said, referring to a peace plan drawn up by UN-Arab League envoy Kofi Annan.
"Anything that interrupts their work and endangers the lives of UN personnel is something we would condemn."
Meanwhile, Annan urged Syria to stop delaying an agreement on allowing UN access to more than one million Syrians in need of assistance, saying the process had been "very slow."
Annan "remains extremely concerned about the plight of one million Syrians in need of humanitarian assistance," said Nesirky.
Elsewhere today, three civilians including a child were killed as troops fired on a refugee camp in Daraa province for Palestinians and Syrians displaced from the Israeli-annexed Golan, the Observatory said.
Regime forces also killed a young man in a raid on Mleiha al-Aatsh village of Daraa, the watchdog said.
In the central province of Homs, a civilian was killed in the rebel-held town of Rastan, which was under regime bombardment, according to the Syrian Observatory.(ST-16/05)
