Washington, Feb 29 (IANS): U. President Donald Trump spoke to his Turkish counterpart Recep Tayyip Erdogan on the phone over the escalating tense situation in northwest Syria, said the White House.

In the call on Friday, Trump voiced Washington's support for Ankara's "efforts to de-escalate the situation in northwest Syria and avoid a humanitarian catastrophe", Xinhua news agency quoted the White House as saying in a statement.

Trump and Erdogan also called for Syria, Russia and Iran to halt their offensive before more civilian deaths, according to the statement.

A total of 33 Turkish soldiers were reportedly killed in air strikes occurring in Idlib on Thursday, a heavy loss for Ankara following days of clashes between Turkey-backed forces and Russia-backed Syrian government troops and escalating tension between Turkey and Russia.

UN Secretary-General Antonio Guterres on Friday called for an immediate ceasefire in Idlib "before the situation gets entirely out of control".

NATO Secretary General Jens Stoltenberg on Friday urged de-escalation in Syria and highlighted the organization's solidarity with Ankara.