Turkish troops and allied Syrian forces seized control of the northwestern city of Afrin from the Kurdish People's Protection Units (YPG) militia on Sunday.

Speaking after a press conference in Stockholm, Saleh Muslim, the former co-chair of the main Syrian Kurdish political movement, the Democratic Union Party (PYD) said Turkey wouldn't have succeeded without Russian backing.

"We are disappointed by the Russians because they had some obligations when they came to Syria... they promised that they were going to protect the Syrian territory," Muslim, 67, told AFP.

"Russia didn't do anything (about the Turkish incursion), they gave the green light to Turkey and everybody is sure that if (Turkey) didn't have the green light from Russia then they wouldn't do it," he added.

Ankara began its offensive in January against the Kurdish People's Protection Units (YPG) militia -- the military wing of the PYD -- which it says is allied with the outlawed Kurdistan Workers' Party (PKK) waging an insurgency against Turkey since 1984.

The PKK is blacklisted as a terror organisation by Turkey and its Western allies.

But the YPG has been working closely with the United States against the Islamic State extremist group in Syria, much to Turkey's chagrin.

Some 250,000 civilians fled the violence in Afrin and dozens of others were killed, as well as around 1,500 Kurdish fighters, according to the UK-based Syrian Observatory for Human Rights said.

Defying a Turkish arrest warrant, Muslim's visit to Stockholm comes nearly a month after he was briefly detained in Prague.

A Czech court later released him and the nation's prosecution later closed a preliminary extradition procedure.

Muslim is wanted by Turkey over a February 2016 bombing in Ankara that killed 29 people that the Turkish authorities blamed on Kurdish militants.

He has been charged in the case and faces 30 life sentences if found guilty.

Muslim vehemently denies the charges and says Turkey is trying "to silence him".