SARAJEVO (Bosnia and Herzegovina), Sept 21 — Russia and Turkey have agreed on borders of the demilitarised zone around Syria’s Idlib, Russia’s top diplomat said today, part of a deal aimed to prevent a military assault on the last rebel enclave.

"Just yesterday or the day before, the militaries of Russia and Turkey agreed the concrete frontiers of the demilitarised zone,” Russian Foreign Minister Sergei Lavrov said after talks with his Bosnian counterpart Igor Crnadak.

Moscow says the demilitarised zone would help stop attacks from Idlib on Syrian army positions and Russia’s military bases in the region.

Russian President Vladimir Putin and Turkish counterpart Recep Tayyip Erdogan agreed the establishment of the 15 to 20 kilometre (9.3-12 miles) zone on Monday after talks that lasted more than four hours.

Security in the zone will be overseen by Turkish contingents and Russian military police. The agreement will prevent military action against Idlib, Russia’s defence minister said.

"It’s an intermediate step... but a necessary step,” Lavrov said of the zone.

"By mid-October, all (fighters of the Al-Nusra Front) must leave this demilitarised zone, and all heavy military equipment must be pulled out of there,” he said.

Russia is a key ally of Syrian President Bashar al-Assad’s regime, helping the Syrian government establish control over most of the country’s territory after intervening in the multi-front conflict in 2015.

Turkey, however, backs opposition fighters seeking to oust the Syrian leader. It has said a large-scale offensive against the rebels could trigger a mass exodus towards its border. — AFP