Britain has said it is “deeply concerned” about the prospect of a Turkish invasion of Kurdish-held territory in Syria and that its foreign secretary has communicated its unhappiness with Donald Trump’s announcement of a US troop withdrawal from the area.

The prime minister’s official spokesman declared “we do not support the action” Turkey had said it was preparing, and said Dominic Raab had complained about the US decision in a phone call on Monday night with Trump’s secretary of state, Mike Pompeo.

The hardening of the UK position emerged as MPs debated the Syrian crisis in the Commons, where Andrew Murrison, a junior Foreign Office minister, repeatedly said the UK was opposed to an anticipated Turkish offensive.

“We have been consistently clear with Turkey that unilateral military action must be avoided as it would destabilise the region and threaten efforts to secure the lasting defeat of Daesh,” Murrison told MPs.

The junior minister said the situation was “in the diplomatic space” when asked what actions the UK was taking by Crispin Blunt, a Conservative former chairman of the foreign affairs select committee. “This is a dynamic situation and we have to respond to whatever happens,” Murrison added.

The threat of a Turkish offensive marks the end of a US-Turkish arrangement established in August under which troops from both countries carried out joint patrols in a “safe zone” along the border keeping Turkish and Kurdish forces apart.

The safe zone deal was due to forestall a Turkish military offensive that has been threatened since Trump announced last December the 2,000 US special forces stationed in Syria would leave. Ankara sees the Kurdish-led Syrian Democratic Forces as indistinguishable from Kurdish insurgents inside Turkey and views them as a serious security threat.

Kurdish forces have spearheaded the campaign against Islamic State in the region and are regarded as some of the west’s most loyal and effective allies.

What was initially a Kurdish force of ground troops with air and logistical support from a US-led coalition has expanded into an administration controlling 30% of Syria east of the Euphrates River. Kurdish-run north-east Syria is the largest part of the country outside the control of President Bashar al-Assad.

Condemnation of Trump’s announcement and the prospective Turkish invasion was near universal in the Commons, where the minister was responding to an urgent question brought by the Tory former defence minister Tobias Ellwood.

Emily Thornberry, Labour’s foreign affairs spokesperson, said Trump’s decision would “open the door to a Turkish invasion of Syria and the subjugation of the Kurdish people”, who she said were “the very people who led the fight against Daesh [Islamic State]”.

Thornberry asked why the US president felt able to say on Monday night that “the UK is very thrilled” at his decision to withdraw US troops, pressing him on what Raab had told his counterpart in last night’s phone call.

“No idea where that came from,” Murrison replied. “It certainly isn’t based upon the conversation that my right honourable friend [Raab] had with Secretary of State Pompeo last night”.

The minister later tried to downplay the effect of the US announcement, saying it involved only the withdrawal of 50 troops from the Syria-Turkey border, although Trump had repeatedly said his plan was to remove the 1,000 troops stationed in the Kurdish controlled part of Syria.

Lloyd Russell-Moyle, a Labour backbencher who chairs the all-party parliamentary group on north-east Syria, called on the UK “to suspend sharing any intelligence information with Turkey so they can’t use it against one of our allies” and provide further support to the Kurdish military, the Syrian Democratic Forces.

Murrison did not respond to Russell-Moyle’s specific requests, but said the UK had previously supported the SDF in the fight against Isis. The minister also would not say if the UK had any plans to escalate the crisis by asking for the issue to be discussed at either the UN security council or the North Atlantic Council, which governs Nato.