Reuters - The military chiefs of staff of Syria, Iran and Iraq will hold a rare meeting in Damascus to discuss �ways to combat terrorism�, the pro-Syrian government al-Watan daily reported on Monday.

The paper gave no further details of what would likely be discussed at the meeting, or its timing and location.

Iran has been one of the most steadfast supporters of Syrian President Bashar al-Assad during eight years of war, and is also a close ally of Iraq.

The United States has said it wants to limit what it calls Tehran�s destabilizing influence in the Middle East, including in Iraq and Syria.

A small U.S. military force in eastern Syria is aiding the Kurdish-led Syrian Democratic Forces (SDF), which is fighting Islamic State and controls a long stretch of the border with Iraq.

A U.S. military base at Tanf in southeast Syria also sits near the Damascus-Baghdad highway, closing the main border crossing between the two countries.

Iran and the regional militias it supports have helped both the Syrian and Iraqi governments with their own military campaigns against Islamic State.

On Sunday, the Iranian Fars news agency reported the Iranian armed chief of staff, Major General Mohammad Baqeri, as saying the U.S. presence in Syria was illegal but would be short lived.

�Forces who are in this country without coordinating with the government of Syria will leave Syrian soil sooner or later,� it quoted him as saying after his arrival in Damascus.

He also noted the presence of foreign forces in Idlib, in northwest Syria, where Turkey has posted military observation units along the front line between the government and rebel forces, as being illegal.

The Turkish presence in Idlib and the northwest is part of a deal between Ankara and Assad�s strongest ally Russia to stop more warfare in that area.

Reporting by Angus McDowall; Additional reporting by Babak Dehghanpisheh in Geneva; Editing by David Holmes