An explosion has rocked military vehicles accompanying a convoy of U.N. monitors in Syria on Wednesday, a day after international mediator Kofi Annan warned that ongoing anti-government unrest could cause Syria to descend into civil war.

The blast in the southern flashpoint city of Daraa left at least six soldiers wounded. The observer mission head, Major General Robert Mood, was part of the convoy but neither Mood nor any other monitors was wounded.

The observers have been fanning out across Syria to monitor compliance with a shaky cease-fire, which is part of a peace plan brokered by Mr. Annan.

On Tuesday, Mr. Annan said the observer mission was “possibly the only remaining chance” to stabilize Syria. After a U.N. Security Council briefing, he told reporters there was “profound concern” the country could otherwise slide into civil war.

Meanwhile, the government resumed vote-counting from Monday's parliamentary elections that opposition groups dismissed as a sham.

The state-run SANA news agency said officials had finished tallying votes in several several regions, including Idlib and Daraa.

More than 7,000 candidates are vying for seats in the 250-member parliament. The election is a government effort to show that it is enacting democratic reforms, but opposition groups say the election lacks credibility because the government has continued its year-long crackdown on dissent.

The government has blamed armed terrorist groups for much of the unrest.

The U.N. says more than 9,000 people have been killed since the violence related to the anti-government uprising which erupted over a year ago.