Representatives of some of Syria's leading pro-government tribes on Friday rejected support from Jordan's King Abdullah II against the Islamic State group, accusing him of backing "terrorists."

Their comments came after the Jordanian monarch, in a meeting with tribal leaders in his country, pledged to support tribes in areas of Syria and Iraq where the jihadists are operating.

"It is our duty as a nation to support the tribes in eastern Syria and western Iraq," the king was quoted as saying by Jordanian official media during the meeting on Sunday.

While the pledge was welcomed by some tribes in Iraq, the comments were received differently in Syria, where the government accuses Amman of backing rebels fighting to oust President Bashar Assad.

"The Syrian tribes firmly and definitively reject any call or project to deprive them of their national, Syrian, Arab essence," said Sheikh Mohamed Fares Al-Abd Al-Rahman of the Tay tribe.

Speaking underneath a photo of Assad at a Damascus press conference, he expressed "surprise" at King Abdullah's comments.

The king, he said, "is well aware of who is behind the terrorists and where their operations rooms and military training camps are located, where their funding and weapons come from, and how they enter our country from Jordan."

Syria's government has long accused Jordan of facilitating the uprising against Assad, in particular by allowing fighters to cross its border freely.

Damascus deems all those fighting against the regime "terrorists," and makes no distinction between Western and Arab-backed rebels and IS jihadists.

Jordan is hosting a U.S.-run program to train Syrian rebels to fight against the Islamic State and is reportedly a key backer of rebels who have made several gains against the government in southern Syria recently.

In a statement, the tribes urged Jordan "to provide real support to Syria against the conspiracy it faces."

"Our army will be the powerful guarantor of the unity of the country and the Syrian nation," the statement said.

Syria is home to around 20 major tribes, some of which have members in Iraq and Jordan.

The Sunni tribes in Syria are split between backers of the government, supporters of the opposition and some who have remained neutral.

More than 230,000 people have been killed in Syria since the conflict began in March 2011 with anti-government demonstrations that were met with a regime crackdown.