Russiainfo-icon is setting up a military base in northwestern Syriainfo-icon in agreement with the Syrian Kurdish YPG militia that controls the area and will be training YPG fighters as part of the fight against terrorism, the militia's spokesman said on Monday.

YPG spokesman Redur Xelil said the agreement with Russia was concluded on Sunday, and that Russian troops had already arrived at the position in the northwestern region of Afrin with troop carriers and armoured vehicles.

The move will likely anger neighbouring Turkeyinfo-icon. Ankara views the YPG as an extension of the Kurdistan Workers' Party (PKK), which is waging an insurgency inside Turkey.

"The Russian presence ... comes in agreement between (the YPG) and the Russian forces operating in Syria in the framework of cooperation against terrorism and to help train our forces on modern warfare and to build a direct point of contact with Russian forces," Xelil said in a written statement. "It is the first (agreement) of its kind," he added.

 Turkey has launched a cross-border offensive along a section of the Turkish-Syrian frontier to prevent further gains by the YPG, which controls swathes of northeastern Syria and the Afrin pocket of northwestern Syria.

The YPG is also allied to the United Statesinfo-icon in the fight against the militant Islamic Stateinfo-icon group in Syria, and is playing a major part in the USinfo-icon-backed offensive against IS's urban stronghold of Raqqa, further east.

"The agreement came into force today," Xelil said, declining to say how many Russian troops had arrived in Jandaris, the place where the base is being established.

Jandaris has previously been shelled by Turkish forces from across the nearby frontier, Xelil added. The militia, which had 60,000 fighters at the end of 2016 -- including its all-female affiliate, the YPJ -- has already formed 10 new battalions since the start of this year, each comprised of around 300 fighters, he said.

"We aspire to exceed 100,000," Xelil said. Asked how soon the YPG aimed to reach this target, he said: "The second half of 2017."

The YPG, or People's Protection Units, effectively serves as the military of the autonomous Kurdish-led

regions which emerged in northern Syria with the retreat of state authority in 2011 that accompanied the outbreak of civil warinfo-icon.