At least nine people have been killed and dozens injured after a car bomb exploded in eastern Syria, reports say.
State television said that the attack was carried out by a suicide bomber in the city of Deir al-Zour.
The blast took place near military intelligence offices, according to a Syrian opposition group.
It is just the latest in a series of blasts near Syrian security agency buildings, which appear to bear the hallmarks of al-Qaeda operations.
No group has said it carried out the attack. A Syrian foreign ministry spokesman said that the bomb contained 500kg of explosives.
Syrian state television broadcast scenes from the aftermath of the explosion, showing extensive damage to buildings, some still on fire, and mangled vehicles. A large column of black smoke rose above the city.
The blast hit the Ghazi Ayyash area of the city on a road said to house several military facilities and a military residential complex. UN observers based in the city were said by officials to have visited the site of the blast.
The explosion comes a day after state news agencies reported that authorities had foiled a bomb attack in the city and detained several suspects.
Such attacks have increased across Syria this year, with the government blaming al-Qaeda militants within the opposition movement, reports the BBC's Jonathan Head in Istanbul.
A twin suicide bombing in Damascus last week killed 55 people in the deadliest attack on the city since the uprising against President Bashar al-Assad started last year.
Opposition activists say they have evidence that suggests elements of the security forces were behind some of the attacks, our correspondent says.
Earlier this month, Syria sent to the United Nations a list of 26 names of foreign nationals it had apprehended, claiming most of them were members of al-Qaeda.
UN Secretary General Ban Ki-moon has said that Islamist militants from al-Qaeda must be behind the deadly blasts in Damascus last week.
Mr Ban also said at least 10,000 people had died in the uprising.
Nearly 260 unarmed UN observers have been deployed in Syria to monitor a ceasefire, which has largely collapsed since it was brokered in March by UN and Arab League representative Kofi Annan.
On Friday, activists said thousands of people took to the streets in the northern Syrian city of Aleppo, which has remained largely loyal to President Assad, in the biggest protests there since the revolt began.
The UN secretary general said their deployment had some "dampening effect" on the violence, but not enough to halt it.