Manama, Bahrain - The US envoy for Syria said on Saturday that Damascus's interim President Ahmed al-Sharaa is to travel to Washington and may sign an agreement to join an international US-led alliance against the Islamic State.

Asked by reporters on the sidelines of the Manama Dialogue in Bahrain whether Sharaa would head to Washington this month, Tom Barrack said "yes," adding that Sharaa would "hopefully" sign up to the Global Coalition to Defeat ISIS.

It would be the Syrian leader's first visit to Washington and his second visit to the US after a landmark UN trip in September, where the former jihadist became the first Syrian president in decades to address the General Assembly in New York.

In May, the interim leader – whose Islamist forces ousted longtime ruler Bashar al-Assad late last year – met with US President Donald Trump for the first time in Riyadh in a historic visit that led to the US leader vowing to lift economic sanctions on Syria.

Formerly affiliated with Al-Qaeda, Sharaa's group Hayat Tahrir al-Sham (HTS) was delisted as a terrorist group by Washington as recently as July.

Since taking power, Syria's new leaders have sought to break from their own radical Islamist past and present a moderate image more tolerable to ordinary Syrians and foreign powers.

The US had already been collaborating with the Kurdish-led Syrian Democratic Forces (SDF) to fight IS in Syria.

The group was long Washington's main ally in Syria and played a vital role in the fight against the Islamic State group in Syria, which ultimately led to the jihadist organisation's territorial defeat in the country in 2019.

The Kurdish forces – who control large swathes of Syria's oil-rich northeast – reached a preliminary agreement with Damascus to integrate into Syria's military and security forces, their leader Mazloum Abdi told AFP last month.