Tensions have mounted in the last three months between rebel-backer Turkey and Syria ally Moscow over President Bashar al-Assad's offensive in northwest Idlib, the last-rebel held region.

Earlier this month, 14 Turks were killed in two separate incidents of regime shelling in Idlib. Two more were killed on Thursday.

"We have no intentions of a face-off with Russia," Turkey's defence minister Hulusi Akar told CNN Turk broadcaster, adding talks would continue with Russian officials.

One of the issues being discussed is the airspace above Idlib and Turkey's expectations for Russia not to get involved, Akar said.

There has been no concrete agreement between Russia and Turkey after two rounds of talks between their respective delegations in Ankara and Moscow earlier this month.

Ankara insists that it wants to avoid a humanitarian disaster but also wants to avoid flow of refugees into Turkey, which is already home to 3.6 million Syrians.

Turkey has 12 observation posts in Idlib province, set up after a deal signed with Russia in the Black Sea resort of Sochi in 2018 to prevent a regime offensive.

- Possible 'Patriot support' -

In addition to the Turkish soldiers killed, the Syrian regime offensive has left hundreds of dead and forced 900,000 people to flee their homes since December.

"There is the threat of air strikes, missiles against our country," Akar told CNN Turk channel, adding: "There could be Patriot support."

He was referring to the US-made anti-missile missiles.

Akar ruled out any US troop support in the interview filmed earlier on Thursday before two Turkish soldiers were killed in Idlib in an air strike blamed on Damascus.

Any delivery of US Patriots would be difficult since Ankara purchased the S-400 Russian air defence system despite Washington's objections and concerns.

Despite this and the remaining threat of US sanctions against Turkey over the purchase, Akar said the system "would be activated... No one should doubt this."

The minister said Turkey still sought to purchase the Patriots, an equivalent of S-400s, despite the US concern over the S-400 system.

He also again criticised the US over its move last year to kick Turkey off its F-35 fighter jet programme as punishment for the S-400 purchase. "We are a partner in the programme, not a customer," he added.

Turkey has warned Damascus of an "imminent" operation if regime forces do not move back behind Ankara's military posts in Idlib.