Beirut: A Kurdish-Arab alliance on Tuesday announced the launch of a major assault against the Islamic State group north of the jihadists` Syrian bastion of Raqa.
"With the participation of all SDF (Syrian Democratic Forces) units, we start this operation to liberate northern Raqa" province, the SDF wrote on Twitter, quoting Kurdish commander Rojda Felat.
The push will be supported by air strikes from the US-led coalition bombing IS in Iraq and Syria, the SDF said.
The SDF was formed in October as an alliance between the powerful Kurdish People`s Protection Units (YPG) and rebel groups including Arab and Assyrian militias.
It said on Twitter that it would clear IS from territory north of Raqa and also secure cities already seized from the jihadists.
But it made no mention of Raqa city itself.
The fresh offensive comes just three days after the highest-ranking US regional commander made a surprise visit to northern Syria.
General Joseph Votel, head of US Central Command (Centcom), met SDF leaders and US military advisors working with Syrian Arab fighters.
He was "in Syria preparing the push to Raqa," anti-IS coalition chief Brett McGurk tweeted.
The US has roughly 200 advisers on the ground in Syria, but no combat units.
Votel`s visit came as the first of 250 more US special operations forces were beginning to arrive.
According to the Syrian Observatory for Human Rights monitoring group, coalition warplanes on Tuesday carried out dozens of strikes north of Raqa city.
Russian Foreign Minister Sergei Lavrov on Tuesday said Moscow was ready to coordinate with both the US and the SDF in the offensive for Raqa.
The SDF has a total of about 25,000 Kurdish fighters and about 5,000 Arab fighters.
With coalition air support, it has expelled IS from key locations across northern Syria, in the provinces of Aleppo, Raqa, and Hasakeh.