Turkish tanks shelled Kurdish-held villages in northern Syria as Prime Minister Ahmet Davutoglu warned Monday that a military campaign by Ankara could "change the balance" in the region.
With its warplanes hitting Kurdish targets in neighbouring northern Iraq again on Sunday, Turkey also called an extraordinary NATO meeting for Tuesday over its cross-border "anti-terror" offensive against Kurdish separatists and Islamic State jihadists.
NATO chief Jens Stoltenberg defended Turkey's right to defend itself but told the BBC "of course self-defence has to be proportionate".
And he cautioned Turkey about burning bridges with the Kurds. "ForTurkish tanks shelled Kurdish-held villages in northern Syria as Prime Minister Ahmet Davutoglu warned Monday that a military campaign by Ankara could "change the balance" in the region. 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 pushed IS out of 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 in the village of Zur Maghar in Aleppo province.
The "heavy tank fire" wounded four members of the allied rebel force and several villagers, the YPG -- which Turkey accuses of being allied to its outlawed Kurdistan Workers' Party (PKK) -- said in a statement.
It said there was later a second round of shelling against Zur Maghar and another village in the same area.
The tank fire was also reported by activists and the Syrian Observatory for Human Rights.
But Turkish officials denied the military was deliberately targeting Syrian Kurds said it was responding to fire from the Syrian side of the border.
"The bombing of the village is out of the question," a foreign ministry official told AFP. "Turkey has its rules of engagement. If there's fire from the Syrian side, it will be retaliated in kind."
Zur Maghar is on Turkish border, east of the town of Jarabulus, which is held by IS.
- Deal with US -
"Instead of targeting IS terrorist occupied positions, Turkish forces attack our defenders' positions," the YPG added.
As the bombardments were going on Davutoglu told a group of Turkish newspaper editors that Turkey'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.
"Why should we be disturbed? If we had been disturbed by Kurdish gains we would have been by Barzani's Kurdish region," he said, referring to the Kurdish autonomous region of northern Iraq.
Turkey has given a green light to the United States to use of its Incirlik air base to attack IS targets in Syria after months of tough negotiations.
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Davutoglu declined to provide details of the agreement but said the concerns of Ankara, which had been pressing 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.
Tensions are running high in Turkey, with police routinely using water cannon to disperse nightly protests in Istanbul and other major cities denouncing 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 suicide bombing in a town close to the Syrian border that killed 32 people.
This incensed Turkey's Kurds, who have long accused the government of actively colluding with IS, allegations the government 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 organisations had been rounded up.
Ankara started its campaign on Friday against IS targets in Syria but then expanded it to PKK rebels in neighbouring northern Iraq who are bitterly opposed to the jihadists.
The strikes seemed to torpedo long-running peace talks, with the separatists saying conditions were no longer in place to observe its ceasefire.
The Turkish army Sunday blamed PKK militants for a deadly car bomb attack that killed two of its soldiers in the Kurdish-dominated southeast, further shaking the truce.
The PKK's military wing, the People's Defence Forces (HPG), claimed the car bomb attack in the Lice district of Diyarbakir province but gave much higher toll of eight soldiers killed.
- 'Don't give up on peace' -
The HPG 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 Wednesday while sleeping in their homes in the southeast, in murders also claimed by the PKK.
Meanwhile Turkey, NATO's only majority Muslim member, called an extraordinary meeting of ambassadors of NATO states on Tuesday for talks on its military operations.
With Washington gladdened by Turkey's readiness to step up its fight against IS, the White House backed Turkey's right to bomb the PKK which the United States categorises as a terror group.
German Chancellor Angela Merkel however urged Davutoglu "not to give up the peace process with the Kurds but to continue it despite all the difficulties," her spokesman Georg Streiter said.