Turkish jets on Wednesday forced a Syrian passenger plane to land at Ankara airport on suspicion that it might be carrying weapons or other military equipment, amid heightened tensions between Turkey and Syria that have sparked fears of a wider regional conflict.

The Syrian Air jetliner was traveling from Moscow when it was intercepted by F16 jets as it entered Turkish airspace and was escorted to the capital's Esenboga Airport, the state-run TRT television reported.

Hours later, Foreign Minister Ahmet Davutoglu said the Airbus A320 with 37 passengers and crew would be allowed to leave, but its cargo had been confiscated.

"There are elements ... that are not legitimate in civilian flights," the state-run Anadolu Agency quoted Davutoglu as saying. He did not provide details but said authorities continued to examine the cargo.

Davutoglu earlier told Turkey's TGRT television that the plane was intercepted on suspicion it was carrying illicit cargo to Damascus.

"If equipment is being carried under the guise of civilian flights or if they are not being declared, then of course we'll inspect it," he said.

"We are determined to stop the flow of weapons to a regime that carries out such ruthless massacres," Davutoglu added. "We cannot accept that our air space be used for such aims."

Hurriyet newspaper's website, citing unidentified intelligence officials, said communications equipment, wireless sets and jammers were found on board. NTV television reported that authorities found "missile parts."

Syrian Information Minister Omran Zuabi declined comment.

Davutoglu said Turkish authorities had also declared Syria's airspace to be unsafe and were stopping Turkish aircraft from flying over the civil war-torn country.

The move comes as tensions between Turkey and Syria are running high. The countries, which were once close allies, have been exchanging artillery fire across the volatile border for days.

Earlier Wednesday, Turkey's military chief vowed to respond with more force to any further shelling from Syria, keeping up the pressure on its southern neighbor a day after NATO said it stood ready to defend Turkey.

Gen. Necdet Ozel was inspecting troops who have been put on alert along the 565-mile (910-kilometer) border after shelling from Syria killed five Turkish civilians in a border town last week. Turkey has reinforced the border with artillery and also deployed more fighter jets to an air base close to the border region.

"We responded and if (the shelling) continues, we will respond with more force," the private Dogan news agency quoted Ozel as saying during a visit to the town of Akcakale.

U.S. Defense Secretary Leon Panetta said Wednesday that Washington has sent troops to the Jordan-Syria border to help build a headquarters in Jordan and bolster that country's military capabilities in the event that violence escalates along its border with Syria.

The revelation raises the possibility of an escalation in the U.S. military involvement in the conflict, even as Washington pushes back on any suggestion of a direct intervention in Syria.

In Syria's largest city, Aleppo, regime troops and rebel fighters exchanged fire for several hours in and around the historic 13th-century Umayyad Mosque, said local activist Mohammed Saeed.

He said rebels were trying to drive out regime troops holed up in the downtown place of worship, and that by nightfall the shooting had stopped. The mosque is one of the landmarks of Aleppo, along with its medieval covered market, or souk, which was largely gutted last month in a huge fire sparked by the fighting.

Rami Abdul-Rahman of the Britain-based Syrian Observatory for Human Rights said local activists told him fighting was restricted to the area near the mosque, but that no fighters entered the site itself. The Observatory relies on reports from a network of activists in Syria.

Aleppo has been the scene of intense fighting, particularly since rebels launched a new offensive two weeks ago to try to dislodge regime troops. The fighting has devastated large areas of the city of 3 million, Syria's former business capital.

Earlier, Syrian activists also said the rebel units of the Free Syrian Army took control of Maaret al-Numan, a strategic city along the main highway in Idlib province that connects the central city of Homs with Aleppo to the north and the capital Damascus.

Abdul-Rahman said the rebels took control of the city late Tuesday. He said the rebels control the western entry into the city, while the military is massing troops along the eastern outskirts for a possible counter offensive.

Fadi Yassin, an activist in Maarat al-Numan, told The Associated Press on Skype that rebels were in control of the city, although fierce fighting continued around the military barracks on Wednesday, three days after the opposition launched a "liberation battle."

"The city has been liberated," Yassin said. "All liberation battles start with small cities and then move on to the major cities."

Holding onto Maaret al-Numan would be a significant achievement for the rebels, enabling them to cut the army's main supply route to Aleppo and Homs, both of which came under bombardment from the regime's helicopters and artillery on Wednesday, according to activists.

The Anadolu news agency reported fighting between Syrian rebels and forces loyal to Syrian President Bashar Assad's regime around the town of Azmarin, in Idlib province, across from the Turkish border. It said Syrians were fleeing homes in the Azmarin region, some crossing into Turkey by boat over the Orontes River, which runs along the border.

Footage from Anadolu showed women, children and elderly men being transported from Syria to Turkey on makeshift rafts and boats.

Private NTV television reported that explosions and automatic weapon fire could be heard in Turkey's Hatay province, coming from Azmarin. It said rebels were clashing with some 500 Syrian government soldiers, and that at least 100 rebels had been injured, some of whom had been brought to Turkey for treatment.

Some 99,000 Syrians, mostly women and children, have sought refuge in Turkey since the start of the conflict.

Also on Wednesday, state-run news agency SANA said Assad appointed Sattam Jadaan al-Dandah as Syria's new ambassador to Iraq. The report did not say when al-Dandah would travel to Baghdad. His predecessor, Nawaf Fares, defected in July, becoming the most senior diplomat to abandon Assad's regime during a bloody 18-month uprising that has morphed into a bloody civil war.

Meanwhile, the U.N. envoy on Syria, Lakhdar Brahimi, arrived in Jeddah, Saudi Arabia, on Wednesday on the first stop of his diplomatic tour of the Middle East. His spokesman Ahmad Fawzi said Brahimi would "hold wide-ranging talks on the prolonged crisis in Syria."


Barbara Surk and Zeina Karam in Beirut and Frank Jordans in Istanbul contributed to this report.