A town in northern Turkey has offered free bus services for migrants who want to make the 550-kilometre trip to the Greek border.

It comes after Turkey, which hosts 3.6 million Syrians, said it could no longer stop those who wanted to make for the European Union.

That announcement came after 33 Turkish soldiers were killed in a Syrian government airstrike in Idlib province on Thursday.

Experts say Turkey wants the EU to pressure Russia to stop supporting Damascus in Syria and agree to a ceasefire.

Tanju Özcan, the mayor of Bolu, said he would lay on buses for as many refugees who wanted to get to the Greek border.

Upon leaving Bolu, he added, the service would travel the 550km route to Edirne, a Turkish region on the border with Greece.

He said: "We prepared a plan with our colleagues and we are committed to arranging free buses for the refugees in Bolu towards the border town of Edirne.

"Refugees willing to go to Edirne can apply to the Bolu municipality and its branches. We are ready to assure the transport whatever the number [of refugees] is."

Ankara's move would break a pact made between the EU and Turkey in 2016 in which the latter agreed to curb the number of refugees and migrants travelling to Europe.

The free buses will travel hundreds of kilometres to Turkey's border with Greece Google Maps

But Turkey's turnaround on this pact has been prompted by recent escalations in Syria - most recently the deaths of 33 Turkish soldiers in an airstrike on Thursday in Idlib - which have rekindled fears that a further refugee crisis could be on the horizon.

"Ankara wants the EU to do more to pressure Russia to stop supporting the Syrian government and agree to a ceasefire, and for the EU to provide more financial support to cope with refugees," Luigi Scazzieri, a research fellow at the Centre for European Reform, told Euronews.

He added: "Turkey knows that Europe does not want refugees and is saying it will let them through to Europe in order to push the EU to help it manage refugees and hoping that Europe will pressure Russia to de-escalate in Syria."

Meanwhile, the EU has called on Turkey to "honour its commitments" to the 2016 pact, while one MEP has said the tactic is "dreadful".

Dutch politician Kati Piri said: "How this dreadful act, however, could justify using Syrian refugees as blackmail towards EU is beyond comprehension."