TEHRAN, Iran (AP) — Special envoy Kofi Annan said today in Tehran that Iran could help solve the crisis in Syria, where activists reported fresh violence near the capital Damascus a day before an international cease-fire is supposed to take effect.

Iran is one of Syria’s strongest allies, and former U.N. chief Annan went there to bolster support for his faltering plan to stop the country’s slide toward civil war.

“Iran, given its special relations with Syria, can be part of the solution,” Annan said during a news conference with Iran’s Foreign Minister Ali Akbar Salehi. “The geopolitical location of Syria is such that any miscalculation and error can have unimaginable consequences.”

The conflict in Syria is among the most explosive of the Arab Spring, in part because of the country’s allegiances to powerful forces including Lebanon’s Hezbollah and Shiite powerhouse Iran. The uprising that began more than a year ago seeks the ouster of authoritarian President Bashar Assad.

Iran has opposed any foreign intervention in the crisis and Salehi insisted that “change in Syria” should come under the leadership of Assad.

Syria’s regime defied the Tuesday deadline to pull out troops from cities and towns that was set in the deal brokered by Annan and launched fresh attacks on rebellious areas.

But Annan insists there is still time to salvage the truce by 6 a.m. Thursday, the deadline for government and rebel fighters to cease all hostilities.

“We’ve been in touch with them (Syrian rebels) and have had positive answers from them. … I think by 6 in the morning on the 12th, Thursday, we should see a much improved situation on the ground,” Annan said.

“It is possible to do it and it should be in the interests of the people of Syria,” he added.

Turkey’s Deputy Prime Minister Besir Atalay, who met Annan on Tuesday, said the international envoy “appeared worried to me.” Atalay told Turkey’s TV 24 channel that the Syrian regime is not fulfilling its promise and while withdrawing its forces from one area, it is deploying them in an another.

He added that if Annan’s plan does not succeed in ending the violence in Syria, “the world will rethink. This time, the U.N. Security Council will have no excuses. It will be more difficult to use their veto right.” He was referring to Russian and Chinese vetoes of two past Security Council resolutions condemning Assad’s regime for the crackdown on protesters.

There was more violence today, putting the chances of a truce even deeper in doubt. Syrian troops took control of large parts of villages and towns near the border with Turkey.