Turkey's president warned a fresh migrant crisis could only be resolved if Europe supports its efforts in Syria, as violent clashes broke out between refugees and police on the Greek border.
Thousands of migrants have massed at the Greek frontier since President Recep Tayyip Erdogan announced last week that they would no longer be prevented from trying to enter Europe.
A Turkish official claimed one migrant was killed and five injured by live fire from the Greek side.
The claim was denied by Athens, but an AFP photographer earlier saw a migrant shot in the leg as a group of refugees tried to cut their way through the fencing near the official crossing at Pazarkule.
The group then threw stones at the Greek police, who responded with tear gas, while multiple shots and cries were heard.
Speaking in Ankara, Erdogan said Europe must support Turkey's "political and humanitarian solutions in Syria" if it wants to resolve the situation.
Turkey already hosts some four million refugees, most of them Syrians, and has been fighting the Syrian regime in a bid to prevent another influx from Idlib, the last rebel stronghold, which has been under sustained attack by Damascus since December.
Close to one million people in Idlib have been displaced by the regime assault, which is backed by Russian air power, though they are currently blocked from entering Turkey.
Erdogan said he hopes a ceasefire would be "swiftly established" when he meets his Russian counterpart Vladimir Putin in Moscow on Thursday.
- Ceasefire? -
Despite being on opposing sides of the nine-year war, Turkey and Russia have kept lines of communication open.
But the relationship has been heavily strained as more than 50 Turkish soldiers have died in Idlib in recent weeks.
The defence ministry said Wednesday that three soldiers had been killed by regime fire in the past 24 hours.
Turkey said it had "immediately" retaliated, and the Syrian Observatory for Human Rights said nine regime troops were killed by Turkish drone strikes in the Saraqeb area.
Ankara officially announced an offensive against Syrian forces over the weekend, demanding they pull back behind lines agreed under the 2018 Sochi deal with Russia.
"We expect Russia to fulfil its promises as a guarantor country and stop the regimes attacks and to use its influence to ensure the regime adheres to the Sochi deal's borders," Turkish Defence Minister Hulusi Akar said, NTV broadcaster reported.
But many say Russia is determined to see the Syrian government take back full control of its territory.
"There might be a ceasefire announced after the talks between Putin and Erdogan but it'll be for show," a Western diplomat told AFP.
"I believe Putin will tell Erdogan that's it for his actions in Syria."
- Support Turkey -
The EU has slammed Turkey for what it says is "blackmail" over the migrants issue.
It has promised 700 million euros ($777 million) to deal with the crisis on the Greek frontier, and dispatched a rapid intervention team from its border agency Frontex.
Turkey agreed in 2016 to stop the flow of refugees in exchange for billions of euros, but says the EU has failed to honour other parts of the deal, such as visa liberalisation and an improved customs agreement.
Erdogan upped the ante on Wednesday, saying in a speech: "If European countries want to resolve the issue, they must support Turkey's efforts for political and humanitarian solutions in Syria."
He also told journalists he had asked US President Donald Trump for ammunition.
EU foreign policy chief Josep Borrell and Council President Charles Michel were both in Ankara for talks on the issue.
Erdogan criticised the Greek response, saying: "The Greeks -- who are resorting to any means to stop refugees coming into their country, even drowning them or killing them with live ammunition -- they shouldn't forget they might need this same mercy one day."
A Syrian refugee named Mustafa told AFP the Greek authorities were shooting at them.
"Whoever goes is immediately hit, they threw tear gas," he said, speaking near the border in Turkey's Edirne province.