ANKARA - Turkey on Saturday sent more tanks into the northern Syrian village of al-Rai to fight Islamic State extremists, opening a new front after its intervention last month against the group, state media reported.

The tanks crossed into the village from the Turkish province of Kilis to provide military support to Syrian opposition fighters as part of Turkey's "Euphrates Shield", state-run Anadolu news agency said.

At least 20 tanks, five armoured personnel carriers, trucks and other armoured vehicles crossed the border after noon, Dogan news agency said.

Turkish Firtina howitzers fired on IS targets as the contingent advanced, Dogan said. Euphrates Shield is Ankara's most ambitious operation during the five-and-a-half-year Syria conflict, backed by the tanks as well as war planes and special forces providing support to rebels.

The goal is to remove IS from its border and to halt the westward advance of the Kurdish People's Protection Militia (YPG). US President Barack Obama's anti-Islamic State envoy Brett McGurk said on Twitter US forces hit jihadist targets overnight on Friday with a "newly deployed" mobile rocket system close to the Turkish border with Syria.

The US embassy in Ankara said on the social media website it was the "latest step in US-Turkey cooperation in the fight against ISIL (IS)".

Meanwhile, Turkish war planes destroyed two IS targets in Wuguf in southern al-Rai between 10:00 GMT and 10:24 GMT, the Chief of Staff said, quoted by NTV television.

The statement also said two villages were captured by rebels on Saturday in the al-Rai region. In the last few months, al-Rai has repeatedly changed hands between rebels and IS. Ahmed Othman, a commander in pro-Turkey rebel group Sultan Murad, told AFP in Beirut that his group was now "working on two fronts in al-Rai, south and east, in order to advance towards the villages recently liberated from IS west of Jarabulus".

Othman said it was the first phase of their plans. "We want to clear the border area between al-Rai and Jarabulus from IS, before advancing south towards al-Bab (the last IS bastion in Aleppo) and Manbij (controlled by pro Kurdish forces)."

After the Kurds' success in Manbij, they said they wanted to advance and link their other two "cantons" in northern Syria, Kobane and Afrin. But Turkish President Recep Tayyip Erdogan said on Friday that Turkey would not allow the group to create a "terror corridor".

Meanwhile, more than 100 Kurdistan Workers Party (PKK) militants were either killed or wounded in clashes with Turkish security forces on Saturday, the military said. It was one of the highest casualty tolls in a single day of the conflict in recent years. Turkey's largely Kurdish southeast has been rocked by waves of violence following the collapse of a 2-1/2-year ceasefire between the state and the PKK last year.

The military said in a statement that more than 100 PKK militants had been "neutralised" in clashes, without specifying how many were killed and how many wounded. It said most had been taken back to northern Iraq, where the PKK has mountain camps.

Turkey's southeast has seen heavy fighting in recent days in Hakkari province, near the border with Iraq, and in Van province, near the border with Iran.  Five Turkish security force members were killed and six more were wounded in clashes in Hakkari, security sources told Reuters.