ISTANBUL — Turkey’s prime minister sharply criticized the U.N. Security Council on Saturday for its failure to agree on decisive steps to end Syria’s civil war, as NATO ally Germany backed the Turkish interception of a Damascus-bound passenger jet earlier in the week.

Recep Tayyip Erdogan told an international conference in Istanbul that the world was witnessing a humanitarian tragedy in Syria.

“If we wait for one or two of the permanent members ... then the future of Syria will be in danger,” Erdogan said, according to an official interpreter.

Russia and China, two of the five permanent Security Council members, have vetoed resolutions that sought to put concerted pressure on Damascus to end the conflict and agree to a political transition.

Erdogan called for a reform of the Security Council, which he called an “unequal, unfair system” that didn’t represent the will of most countries.

He spoke as Foreign Minister Ahmet Davutoglu met with Arab and European leaders amid growing tensions between Turkey and neighboring Syria.

Davutoglu held talks Saturday with Arab League chief Nabil Elaraby, German Foreign Minister Guido Westerwelle and U.N. envoy on Syria Lakhdar Brahimi. He told reporters after the meetings that Turkey was prepared to use force again if it was attacked, just as it did last week when a shell fired across the border from Syria killed five Turkish villagers.

“If a similar incident occurs again from the Syrian side, we will again take counter action,” Davutoglu told reporters, while stressing that the border between Syria and Turkey is also the frontier of NATO.

One week after the shelling, Turkey intercepted a Syrian passenger plane en route from Moscow to Damascus and seized what it said was military equipment on board.

Syria denounced the move as air piracy, while Russia said the cargo was radar parts that complied with international law.

The state-run Syrian news agency SANA reported late Saturday that Syria decided to ban Turkish Airlines flights from Syrian airspace.

Germany’s foreign minister backed Turkey on Saturday, saying Berlin would have acted the same way if it believed weapons were being transported to Syria over its airspace.

“It’s not just about weapons. Weapons need to be steered. Weapons need to be delivered,” Westerwelle said. “These are all things that don’t need to be tolerated.”

But he cautioned the situation between Turkey and Syria could quickly escalate out of control.

“The danger of a ‘wildfire’ is very big,” said Westerwelle, who also met briefly with Abdelbaset Sieda, head of the Syrian National Council opposition group. “If that happens, then this can become a devastating conflict for the whole region.”

In Syria, activists said Saturday that army troops clashed with rebels on several fronts across the country, including in Aleppo, the largest city.

Amateur video posted online Saturday shows the aftermath of what is described as an artillery attack on a neighborhood in Aleppo. The video shows a large cloud of gray smoke pushing through a narrow street lined by apartment blocks. Residents then converge on a damaged building. “Is anyone in there?” one of the men is heard calling out as others try to put out small flames with pieces of cloth.

Eventually, rescuers are seen pulling at least two bodies out of the building. One has a bloody face, and another is carried away on a stretcher, amid shouts of “Allahu Akbar,” or “God is Great.

The authenticity of such videos cannot be confirmed independently, since Syria imposes tight restrictions on foreign journalists.

The Britain-based Syrian Observatory for Human Rights, an activist group, said at least two people were killed in the shelling.

Another amateur video posted Saturday showed the scattered, burning wreckage of what appeared to be an aircraft. Several gunmen stood near the debris, as civilians rushed to the scene. The narrator said video was shot in the countryside west of Aleppo.

Rami Abdul-Rahman, the head of the Observatory, said he was told by local rebel fighters in the area that they had shot down the plane. The video showed flames shooting out of what appeared to be left of a wing or tail, and other wreckage a few dozen yards away.

The claim could not be verified independently.

Opposition fighters have claimed to have shot down helicopters and warplanes in the past, although the regime blamed most of the problems on mechanical difficulties.

Over the past month, rebels overran two air defense bases, including one on Friday near Aleppo. This would give them access to heavy weapons, though experts questioned whether they would be able to make use of any missiles they may have spirited away.

More than 32,000 people have been killed in Syria since a revolt against President Bashar Assad erupted 19 months ago. Hundreds of thousands of Syrians have fled the fighting, which has devastated whole neighborhoods in Syria’s cities and towns.

The Observatory, which relies on a network of activists on the ground, said regime forces were pounding the rebel stronghold of Homs in central Syria with mortar fire and artillery Saturday. The southern province of Daraa, the birthplace of the revolt, also sustained shelling by the Syrian army throughout Saturday. Fighting between army troops and rebels raged around Idlib province, in and around Aleppo and on the outskirts of the capital Damascus, the Observatory said.

Earlier, Syria’s state-run news agency reported that Damascus supported a proposal by Russian Foreign Minister Sergey Lavrov to find a “mechanism of direct security communication between Syria and Turkey.”

SANA reported that Syrian government officials and Russia’s ambassador in Damascus discussed ways to establish a joint Syrian-Turkish security committee that would “control the security situation on both sides of the border in the framework of respecting the national sovereignty of the two countries.”

Turkey has made no comment on the proposal, and it is unclear whether Moscow has presented it to the Turkish government yet.