A bomb exploded in central Damascus on Wednesday close to several military buildings and a hotel housing United Nations observers, wounding three people and sending a pillar of black smoke into the sky above the Syrian capital.
Syrian deputy foreign minister Faisal Mekdad said none of the UN monitors was hurt in the explosion.
"This is another criminal operation which proves the barbaric nature of those who carry out these attacks," Mekdad said.
The bomb, in a car park behind the hotel, blasted open the fuel truck when it detonated. A row of white UN vehicles parked nearby was covered in ash and dust.
Although the explosion occurred close to the hotel, it was not clear what the target had been. The area is home to a Syrian army officers' club and a building belonging to the ruling Baath Party. It is also not far from the army command.
Iran building militia for Syria, says US
The US has accused Iran of playing a major role in supporting the Syrian regime by helping to build and train a militia to fight opposition groups.
Chairman of the US joint chiefs of staff, General Martin Dempsey, said Iran was training a militia made up of Syrian Shia Muslim fighters.