Clashes between the Syrian army and rebels at a border post brought the civil war close to neighbouring Iraq, where troops fired warning shots into the air, residents, officials and a Reuters reporter said.

Insurgents seized control of half of the northeastern Syrian town of Yaarabiya, including a border post with Iraq, in a battle with forces loyal to President Bashar al-Assad on Friday and early Saturday, the pro-opposition Syrian Observatory for Human Rights, a monitoring group, said on Saturday.

The fighting on Iraq's doorstep shows how Syria's near-two-year conflict could spill over its borders, threatening to drag in neighbouring countries and further destabilise the region.

Iraqi troops on the other side of the border from Yaarabiya fired warning shots, residents, local officials and a Reuters reporter said.

On Friday, a Scud missile fired from Syrian territory landed near a village opposite Yaarabiya, causing no damage but terrifying locals, the mayor of the town of Telefar, near the Rabia crossing, said.

A Syrian rebel commander told pan-Arab satellite television channel al-Arabiya the Iraqi army fired across the border at Syrian rebels following the Scud incident, but residents and Iraqi military sources denied the report.

Rebel commander Brigadier Selim Idris also told al-Arabiya some Syrian army soldiers fled into Iraq after rebels took the crossing, the second post on the Iraq border to fall into rebel hands.

A medical source from a hospital in Telafar said one corpse and four wounded had been delivered there, identifying them as Syrians, probably from the regular army.

"We have been hearing the sound of explosions and guns in Yaarabiya for the past three days," said Ali Shibaib, who lives 300 metres from the border post in Iraq.

"The Syrian regular army troops are stationed between the Iraqi army and the Free Syrian army," he added.

The Free Syrian Army is the main rebel force.

The conflict in Syria has previously spilled into Iraq. In September, a five-year-old girl was killed when three rockets struck a border town in the al Qaim area.

Opposite another Syrian border, Israeli soldiers also found fragments of mortar shells that fell near an Israeli settlement in the occupied Golan Heights on Saturday. No casualties or damage was caused and United Nations observers were notified, an army spokeswoman said.

Israel seized the Golan from Syria in a 1967 war and later annexed it.

Iraq's precarious sectarian and ethnic balance has also come under strain from the conflict next door, where mainly Sunni Muslim insurgents are fighting to overthrow Assad, who is backed by Shi'ite Iran.

Iraqi Prime Minister Nuri al-Maliki, a Shi'ite Muslim, says his government has a policy of non-interference in Syria.

Syria and Iran on Saturday condemned a move by the United States to give non-lethal aid to rebels fighting to topple Assad, accusing Washington of double standards.

"I do not understand how the United States can give support to groups that kill the Syrian people," Syrian Foreign Minister Walid al-Moualem said at a news conference in Tehran with Ali Akbar Salehi, Iran's foreign minister.-Reuters