Turkish President Recep Tayyip Erdogan has said he has rejected a call from US President Donald Trump to declare a ceasefire and halt Turkey's military offensive in Syria.
Turkey's leader also told a group of journalists that he is not concerned about the presence of Syrian government troops moving into the city of Manbij, but does not want Syrian Kurdish fighters to remain.
Turkey launched its military offensive a week ago to clear a border region from Syrian Kurdish forces linked to outlawed Kurdish militants in Turkey.
Mr Erdogan said that "we cannot declare a ceasefire until we clear this region".
Mr Erdogan's comments during a flight back from Azerbaijan were reported by the Turkish newspaper Hurriyet.
But British arms manufacturers can continue to sell arms to Ankara under existing licences.
It comes as Russia has moved to fill the void left the US troops in the conflict-hit region, deploying troops to keep Syrian and Turkish forces apart.
- Video report by ITV News Correspondent Emma Murphy reports on the situation from the Turkish border where families are fleeing. She says Russia is already filling the vacuum in Syria that retreating US forces have left.
Speaking in the House of Commons, Foreign Secretary Dominic Raab said the government would keep any defence exports to Turkey under "very careful and continual review" adding that Britain "takes its arms export control responsibilities very seriously".
"I can tell the House that no further export licences to Turkey for items which might be used in military operations in Syria will be granted while we conduct that review," said Mr Raab in response to an urgent question from Tory former minister Tobias Ellwood.
The foreign secretary also called on Turkey, a fellow NATO member, to "exercise maximum restraint and to bring an end to this unilateral military action".
Mr Raab added: "With close partners, we must at times be candid and clear.
"This is not the action we expected from an ally. It is reckless, it is counter-productive and it plays straight into the hands of Russia and indeed the Assad regime."
Russia has utilised America's withdrawal from the region, with the Kurdish administration striking a deal with Syria's Russian-back president Bashar al-Assad, whose forces began moving into Kurdish-controlled regions to shield them against Turkey.
- ITV News International Affairs Editor Raghee Omar breaks down the situation in Syria so far
Moscow's envoy to to Syria, Alexander Lavrentyev told Russian state news that "no one is interested" in fighting between Syrian and Turkish forces, and that Russia "is not going to allow it".
Turkey began its offensive last week in an attempt to push Kurdish-led forces from the border region.
Dozens of civilians have been killed in the operation so far and at least 160,000 people have been displaced, according to the UN.
Turkey is aiming to remove the Kurdish-led Syrian Democratic Forces (SDF) from the border region.
Ankara says it considers the biggest militia in the SDF a terrorist organisation.
It wants to create a "safe zone" in the area, in order to resettle as many as two million Syrian refugees currently in Turkey.
But the US withdrawal and the subsequent military action has been widely condemned.
Kurdish-led forces have been a key US ally in the fight against the Islamic State (IS) group in Syria.
Some 11,000 Kurds were killed in that struggle and they have described the US withdrawal as a "stab in the back".
There are also fears that the outbreak of fighting could further destabilise the area, leading to a resurgence of IS, as thousands of former fighters are currently being held in northern Syria.
On the ground on Tuesday, there were reports of intense fighting between Turkish forces and the SDF in the town of Ras al-Ain.
Britain's decision to restrict arms sales, following similar moves by other European countries including France and Germany, and comes just hours after US president Donald Trump announced sanctions against Turkey because of the military action.
Mr Trump said he was halting trade negotiations with Turkey and raising steel tariffs.
He added that he would soon sign an order permitting sanctions to be imposed on current and former Turkish officials.
It was also announced that Vice-President Mike Pence will head to the Middle East to lead mediation efforts.
Despite criticism, the US president doubled-down on his decision to remove troops by tweeting: “Anyone who wants to assist Syria in protecting the Kurds is good with me, whether it is Russia, China, or Napoleon Bonaparte. I hope they all do great, we are 7,000 miles away!"
Meanwhile, also on Tuesday, Nato secretary-general Jens Stoltenberg met British prime minister Boris Johnson in London and voiced “deep concern” about the consequences of Turkey’s military intervention.
Speaking outside No. 10, Mr Stoltenberg said: "I am concerned about how this can further escalate the tensions in the region.
“How it can further destabilise the region, and the human suffering.
“And, not least, I am concerned about the consequences for … the gains we have made in fighting our common enemy, Daesh."
Asked about the suspension of arms sales to Turkey, he said: "It reflects that many Nato allies are very critical and are condemning the military operation in northern Syria.”