Arms have flowed to PKK terrorists in Turkey from the group's Syrian branch the PYD, a security source has told Anadolu Agency.

The source, who spoke on condition of anonymity due to restrictions on speaking to the media, said Russia had been supplying the PYD and its armed wing the YPG with weapons in Afrin, a northwestern district in Aleppo province that borders Turkey's Hatay province, since December.

The weaponry included anti-aircraft missiles, the source said.

PKK members have also been provided with light and medium arms by the Syrian government, as well as training in anti-tank tactics, the source added.

The increase in support for boıth the PYD and PKK coincided with increased attacks by the PKK on security forces in Turkey's southeastern Mardin, Diyarbakır and Şırnak provinces since October.

According to the source, the PYD/YPG smuggles weapons across three main points on the Syria-Turkey border - Qamishli to Nusaybin, Kobani to Suruç and Afrin to the Amanos mountains.

Among weapons seized by Turkey's security forces since early last year are anti-tank rockets, fragmentation grenades, M-16 and AK-47 assault rifles and ammunition, Dragunov sniper rifles and ammunition, Glock handguns and anti-aircraft ammunition.

The source said YPG/PYD terrorists had been sent to fight alongside the PKK in Turkey following the end of fighting around the Syrian town of Kobani in September.

Last week, two YPG/PYD snipers were arrested crossing into Turkey through Şanlıurfa province, the source said. In statements to police, the terrorists said they had been sent to fight in Kobani from the PKK's base in the Qandil mountains, northern Iraq, in 2014. They were heading to join fighting around Sur, Diyarbakır, when they were arrested.

According to the Pentagon, the U.S. sent 50 tons of ammunition to the PYD in October 2015. Syrian media has also reported that Russia sent 5 tons of ammunition to a PYD-controlled region in northern Aleppo.

In an interview with The Sunday Times newspaper in December 2015, Bashar Assad said the Syrian regime had sent arms to the PYD.

The PKK is considered a terrorist organization by Turkey, the EU and U.S. but its Syrian affiliates are viewed as partners of the U.S. in the fight against Daesh.