ISTANBUL -- Turkish tanks crossed into Syria to the west of a frontier town seized from the Islamic State group last week, in a "new phase" of an operation aimed at sealing off the last stretch of border controlled by the extremists.
Syrian rebels advancing from Jarablus say they captured three more villages from the extremists on Saturday. Rebels and Turkish forces are now advancing in two directions, to the east from al-Rai and to the west from Jarablus, to seal the border.
The private Dogan news agency reported at least 20 tanks and five armored personnel carriers crossed at the Turkish border town of Elbeyli, across from the Syrian rebel-held town of al-Rai. The new incursion is unfolding about 34 miles west of Jarablus, where Turkish forces first crossed into Syria 10 days ago.
A spokesman for one of Turkish-backed Syrian factions said 100 Turkish troops accompanied 30 tanks across the border, linking up with the rebels at al-Rai. He spoke on the condition of anonymity because he was not authorized to talk about the Turkish troops. .
IS, which once controlled hundreds of miles of territory along the Turkish border and used it to bring in foreign fighters and supplies, now only rules a 13-mile stretch of the frontier. The group has suffered a string of defeats in recent months in both Syria and Iraq.
Some 5,000 U.S. and Turkish-backed Syrian rebels have crossed into northern Syria from Turkey to participate in the so-called Euphrates Shield operation, according to local journalist Adnan al-Hussein, who is embedded with the groups.
Three rockets fired from IS-held territory in Syria meanwhile struck the Turkish border town of Kilis, some 19 miles from Elbeyli, according to the Turkish governor's office, which said one person was lightly wounded. Dogan says rockets have killed 21 Kilis residents and wounded scores since January.
The Turkish military responded to the rockets on Saturday with howitzers, striking two weapons depots and bunkers, and "destroying the locations and the Daesh terrorists there," the state-run Anadolu news agency said, referring to IS by an Arabic acronym.
Turkey's military says its right to self-defense, as well as U.N. resolutions to combat the IS group, justify its Syria incursions.
Turkey and allied Syrian rebels have also fought U.S.-backed Kurdish forces known as the People's Protection Units, or YPG, around Jarablus. Turkey views the YPG as an extension of the Kurdistan Workers' Party, or PKK, which Turkey and its allies consider a terrorist organization.
The U.S. has provided extensive aid and airstrikes to the YPG-led Syria Democratic Forces, which have proven to be highly effective against IS. The Syria Democratic Forces, which also includes Arab fighters, has taking a large swath of territory from the extremists along the border with Turkey and closed in on Raqqa, the de facto capital of the extremist group's self-styled caliphate.
Associated Press writer Philip Issa in Beirut contributed to this report.