France said Sunday it was "worried" after Kurdish authorities reported that hundreds of relatives of foreign jihadists had escaped from a displacement camp in northern Syria, under Turkish assault.

Tunisians voted on Sunday in a presidential runoff pitting a conservative academic against a media magnate fresh out of jail, reflecting a shift in the country's post-revolution political landscape.

Iraqi authorities, under pressure from the streets as well as political and religious forces, on Saturday increased the number of commissions to investigate the deaths of more than 100 people in recent protest.

From October 1 to 6, at least 108 people were killed and more than 6,000 wounded, according to the government's Human Rights Commission. 

Tunisia prepared for Sunday's presidential runoff after the two finalists, both political outsiders, went head-to-head in a rare television debate in a last bid to woo the country's seven million voters.

A US withdrawal from Syria's northern border this week has exposed Washington's Kurdish partners to a Turkish assault, creating conditions for a rapprochement with Damascus that both sides need badly, analysts said.

The main US partner in the years-long battle against the Islamic State group, Kurdish forces were left to fend for themselves after allied US forces pulled back on Monday.

Turkish forces have taken control of the Syrian border town of Ras al-Ain, which has been a focus of its operation against Kurdish militants, the defence ministry said Saturday. 

Pakistan has offered rare backing to Turkey in its offensive against Kurdish forces in Syria, with President Recep Tayyip Erdogan expected to visit Islamabad later this month.

Turkey denied on Saturday targeting a US base in northern Syria after the Pentagon said its troops had come under artillery fire. 

In the vanguard of Syrian revolt before being ripped apart by division and indiscipline, the Free Syrian Army has returned as a key component of Turkey's offensive against Kurdish militants.

Facing a backlash for appearing to greenlight Turkey's assault against Kurdish forces in Syria, President Donald Trump on Friday dialed up pressure on America's NATO ally by threatening crippling sanctions.

The United States was moving to quash accusations of mixed messages and policy reversals over Turkey's offensive into northeastern Syria, which began after Trump ordered US troops to pull back from the border.