ANKARA, Turkey (AP) — Turkish jets on Wednesday forced a Syrian passenger plane to land at Ankara airport on suspicion that it may be carrying weapons, Turkey's foreign minister said, amid heightened tensions between Turkey and Syria that have sparked fears of a wider regional conflict.

A Syrian Air Airbus A320 coming from Moscow was intercepted by F16 jets as it entered Turkish airspace and escorted to the capital's Esenboga Airport, the state-run TRT television reported.

"There are civil aviation rules, planes are required to make clear statements (concerning their cargo)," Turkish Foreign Minister Ahmet Davutoglu said in an interview with Turkey's TGRT television from Athens. The interview was also shown on TRT. "We received information that it was carrying certain equipment in breach of civil aviation rules."

"Should the information (received by authorities) turns out to be true, then whatever is required by international law will be done," he added.

The head of Turkey's civil aviation agency Bilal Eksi said there were 37 passengers and crew on board the plane. According to Moscow's Vnukovo airport, flight RB442 left for Damascus at 3:26 p.m. Moscow time (1126 GMT). It wasn't immediately clear whether this was the plane that was intercepted.

Davutoglu said the passengers were being treated "hospitably" and given meals while the plane's cargo was being inspected.

Officials in the Syrian information and foreign ministries could not immediately be reached for comment.

Davutoglu also said Turkish authorities had 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 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.

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Gen. Necdet Ozel was inspecting troops who have been put on alert along the 910-kilometer (566-mile) border after shelling from Syria killed five civilians in a Turkish border town last week. Turkey has reinforced the border with artillery guns 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 military 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 near the historic 13th century Ummayyad Mosque, said local activist Mohammed Saeed.

Saeed said rebels were trying to drive out regime troops holed up in the downtown place of worship. He said 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 northern city of Aleppo 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 are in control of the town, although fierce fighting continued around the military barracks in the eastern part on Wednesday, three days after the FSA launched a "liberation battle," he added.

"The city has been liberated," Yassin said of Maarat al-Numan in Idlib province. "All liberation battles start with small cities and then moves on to the major cities."

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

Turkey's state-run Anadolu Agency reported fighting between Syrian rebels and forces loyal to Syrian President Bashar Assad's regime around the Syrian 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 on rowing boats over the river Orontes, that runs along the border.

Footage from Anadolu showed women, children and elderly men being taken across the river 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 President Bashar Assad appointed Sattam Jadaan al-Dandah as Syria's new ambassador to Iraq. The report did not say when al-Dandah will travel to Baghdad. His predecessor, Nawaf Fares, defected in July to become the most senior diplomat to abandon Assad's regime during a bloody 18-month uprising that has gradually become 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."

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