"We will keep our defence exports to Turkey under very careful and continual review," Foreign Secretary Dominic Raab said in a statement to parliament.

"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."

Ankara's assault against Kurdish forces launched last week has prompted a chorus of international condemnation. Raab said it had "seriously undermined the security and stability of the region".

"This is not the action we expected from an ally, it is reckless, counterproductive, it plays straight into the hands of Russia and the Assad regime," he told lawmakers.

NATO Secretary General Jens Stoltenberg discussed the volatile situation with British Prime Minister Boris Johnson in Downing Street on Tuesday.

Speaking after the meeting, Stoltenberg said the arms suspensions showed "many Nato allies are very critical and are condemning the military operation in northern Syria".

Britain's halting of military sales to Turkey follows similar moves by key European and NATO allies, including Germany -- one of Ankara's main arms suppliers -- and France.

Meanwhile US President Donald Trump warned Monday that Turkey faces imminent sanctions over its actions but also signalled that Washington would avoid any armed conflict with Ankara.

Turkey's President Recep Tayyip Erdogan has said threats of sanctions and arms embargoes by Western powers will not stop the military offensive.

He vowed to continue the operation targeting the Syrian Kurdish People's Protection Units (YPG), which it sees as a "terrorist" off-shoot of Kurdish insurgents in its own territory, until "our objectives have been achieved".

Erdogan has said he wants to establish a safe zone stretching across northern Syria, to which it can repatriate many of the 3.6 million refugees that it is hosting from the Syrian conflict.