The US and Turkey have agreed to work together to drive Islamic State jihadists from northern Syria, a senior US official said Monday, as Turkish Prime Minister Ahmet Davutoglu said its military could "change the balance" in the region.
The potentially game-changing accord was revealed as Turkey fuelled the growing anger of its Kurdish minority by shelling a Kurdish-held village in northern Syria as its warplanes continued to pound separatist targets in northern Iraq.
"The goal is to establish an ISIL-free zone and ensure greater security and stability along Turkey's border with Syria," the US official, who asked not to be named, told AFP using another acronym for the jihadist group.
Details of the zone "remain to be worked out", the official said during a visit by US President Barack Obama to Ethiopia.
But the official added that "any joint military efforts will not include the imposition of a no-fly zone" -- a long standing Turkish demand.
It would however entail Turkey, NATO'S only mainly Muslim member, supporting US "partners on the ground" already fighting IS extremists.
But many question whether Turkey is more interested in limiting Kurdish capabilities in Syria and Iraq than tackling IS.
Turkey has called an extraordinary NATO meeting for Tuesday over its two-pronged cross-border "anti-terror" offensive against the outlawed Kurdistan Workers' Party (PKK) and IS jihadists.
NATO chief Jens Stoltenberg backed Turkey's right to defend itself but told the BBC Sunday "of course self-defence has to be proportionate".
And he cautioned Ankara about burning bridges with the Kurds. "For years there has been progress to try to find a peaceful political solution," he told Norwegian state broadcaster NRK.
"It is important not to renounce that... because force will never solve the conflict in the long term."
The Kurdish People's Protection Units (YPG) -- which routed IS from the Syrian flashpoint of Kobane early this year with the help of Western air strikes -- said Turkish tanks hit its positions and those of allied Arab rebels overnight in Zur Maghar village in Aleppo province.
The "heavy tank fire" wounded four rebels and several villagers, the YPG -- which Turkey accuses of being allied to the PKK -- said in a statement.
But Turkish officials denied the military was deliberately targeting Syrian Kurds and said it was responding to fire from the Syrian side of the border.
"Turkey has its rules of engagement. If there's fire from the Syrian side, it will be retaliated in kind," a foreign ministry offical said.
Meanwhile, Davutoglu told a group of Turkish newspaper editors that Ankara's intervention would "change the balance" in the region, but ruled out sending ground troops into Syria.
He denied Turkey was worried by Kurdish gains against jihadists in northern Syria, pointing to Ankara's relations with autonomous Iraqi Kurdistan.
Turkey has given the United States the green light to use its Incirlik air base to attack IS after months of tough negotiations.
Davutoglu said Ankara's demands for a no-fly zone were addressed "to a certain extent", according to the Hurriyet daily.
"Air cover is important, the air protection for the Free Syrian Army and other moderate elements fighting Daesh," he said, referring to IS by its Arabic acronym.
"If we will not send ground forces -- and that we will not do -- then certain elements that cooperate with us on the ground must be protected," Davutoglu added.
The cross-border violence has sent tensions soaring in Turkey, with police using water cannon to disperse nightly protests in Istanbul and other major cities against IS and the government's policies on Syria.
Davutoglu ordered the air strikes and artillery barrages after IS violence spilled over into Turkey last Monday with a devastating suicide bombing in a town close to the Syrian border that killed 32 people.
The attack incensed Turkey's Kurds, who have long accused the government of actively colluding with IS, allegations it categorically denies.
Protests raged in a flashpoint Kurdish and leftist district of Istanbul, leaving one policeman dead, as police said 900 people with alleged links to IS, the PKK and other leftist groups had been rounded up nationwide.
Ankara started its campaign on Friday against IS targets in Syria but then expanded it to PKK rebels in northern Iraq who are bitterly opposed to the jihadists.
The strikes seemed to torpedo long-running peace talks with the Kurds, with the separatists saying conditions were no longer in place to observe its ceasefire.
On Sunday, the PKK's military wing, the People's Defence Forces (HPG), claimed the killing of two Turkish soldiers in a car bombing in Diyarbakir province.
It said three more PKK fighters had been killed in Turkish air strikes Saturday, after one was killed in the first wave.
Two Turkish policemen were shot dead in their beds on Wednesday in the southeast, in killings also claimed by the PKK.
Publicly, Washington has given tacit backing to Turkey's actions, saying it "has a right to take action related to terrorist targets".
But there is concern that sustained attacks could cause a rift with Kurdish regional authorities in Iraq, a key partner in fighting the Islamic State inside that country.