Turkish military forces have pushed ahead with their assault in northern Syria, as the conflict rumbles on.

Ground forces have moved deeper into Syria, while airstrikes have been ongoing.

The UN refugee agency said tens of thousands of Syrian residents living near the Turkish border are on the move, with many scrambling to evacuate by any means necessary.

President Recep Tayyip Erdogan confirmed more than 100 "terrorist" Syrian-Kurdish fighters have been killed since the military operation began three days ago.

People run to take cover after mortars fired from Syria. Credit: AP

Turkey's state media reported two Syrian villages had been "cleared of terror", in a reference to Syrian Kurdish fighters. At least 181 targets east of the Euphrates river in Syria had been hit by Turkish airstrikes.

Foreign minister Mevlut Cavusoglu said he planned to move Turkish forces 19 miles deep into Syria until all Syrian-Kurdish forces were "neutralised".

He did not confirm how many troops had crossed into Syria or how many jets were involved in the offensive, but insisted Turkey would create a zone that would allow the "safe" return of Syrian refugees.

President Recep Tayyip Erdogan has threatened to allow Syrian refugees into Europe. Credit: AP

Erdogan has threatened to "open the gates" and let more than three million Syrian refugees into Europe if the EU describes Turkey's military operation as an "invasion".

In a speech to Turkish lawmakers on Thursday, Erdogan defended his country's military action in northeastern Syria.

A number of EU countries have criticised Turkey's military action in the region, including the UK, Germany, France and others.

EU foreign diplomats are due to meet in Luxembourg on Monday to discuss Turkey's military offensive, but Erdogan's threats will heap pressure on an already fraught situation.

Erdogan's threat risks jeopardising the EU-Turkey deal agreed in March 2016, aimed at discouraging refugees from fleeing to European Union nations. In return, Turkey was promised up to €6billion to help the humanitarian crisis.

  • Footage posted by ITV News Correspondent Emma Murphy shows a convoy of Syrian National Army heading to the border at Ceylanpinar as crowds cheer them on

Shortly after Erdogan's strongly-worded statement, the EU's spokeswoman for foreign affairs and security policy called for Turkey to "immediately" stop its military action.

Maja Kocijancic said: "We believe there is no military solution to the conflict in Syria and the only sustainable solution is a political one, the one that was negotiated by the Syrian parties under the UN, that would be negotiated by the Syrian parties under the UN auspices.

"And Turkish legitimate security concerns should be addressed through political and diplomatic means and not, as we said, through military action."

Donald Trump has threatened sanctions against Turkey if it does not "play by the rules".

In a string of tweets, Mr Trump said: "Turkey has been planning to attack the Kurds for a long time. They have been fighting forever. We have no soldiers or Military anywhere near the attack area. I am trying to end the ENDLESS WARS. Talking to both sides.

"Some want us to send tens of thousands of soldiers to the area and start a new war all over again. Turkey is a member of NATO. Others say STAY OUT, let the Kurds fight their own battles (even with our financial help).

"I say hit Turkey very hard financially & with sanctions if they don’t play by the rules! I am watching closely."

US Secretary of State said the withdrawal of American troops from the area was not a "green light" for Turkey to launch an invasion.

Mr Pompeo insisted Turkey had "a legitimate security concern" about the region after president Recep Tayyip Erdogan launched airstrikes and deployed ground forces into the region.

"They have a terrorist threat in their south", Mr Pompeo told PBS News Hour.

He added: "We’ve been working to make sure that we did what we could do to prevent that terror threat from striking the people in Turkey, while trying to achieve what is in America’s best interest: the threat from radical Islamic terrorism emanating from Syria."

When asked whether the US president's decision to pull American troops from the area had given the green light to Turkey's leader Recep Erdogan to launch an attack, Mr Pompeo replied: "Yeah, well that's just false.

"The United States didn't give Turkey a green light."

A UN Security Council will hold a closed meeting on Thursday to discuss the military assault, while Arab foreign ministers will meet on Saturday in Cairo to discuss Turkey's military action.

Turkey said it aimed to create a so-called "safe zone" that would be cleared of Kurdish fighters that Ankara considers to be terrorists.

Ankara considers members of the Kurdish militia to be "terrorists" because of their links to the outlawed Kurdistan Workers' Party, or PKK, which has led an insurgency against Turkey for 35 years, killing tens of thousands. The US and other Western countries also consider the PKK a terrorist group.

Turkey's Foreign Ministry has defended its action and claimed ambassadors of the UN Security Council were briefed its military offensive.

A Turkish army officer guides a comrade driving a tank to its new position on the Turkish side of the border between Syria. Credit: AP

Turkey has been massing troops for days in preparation for an attack against Kurdish fighters in northeast Syria that Ankara considers a terrorist organisation.

French president Emmanuel Macron called on Turkey to "put an end as soon as possible" to its offensive in Syria.

He said their military intervention "may help Daesh rebuild its caliphate".

The secretary-general of NATO is urging Turkey not to "further destabilize the region" through its military action.

Local residents applaud as a convoy of Turkish forces vehicles arrive in Turkey on Tuesday. Credit: AP

Jens Stoltenberg told a news conference in Rome that Turkey, a NATO ally, "has legitimate security concerns," having suffered "horrendous terrorist attacks" and hosting thousands of refugees.

He said NATO has been informed about Turkey's ongoing operation in northern Syria. And he added "it is important to avoid actions that may further destabilize the region, escalate tensions and cause more human suffering."

Mr Stoltenberg will discuss the military action with Turkey's leader on Friday in Istanbul.

  • Syrians in the north-eastern border town of Ras al-Ayn are protesting against Turkey's military offensive