Turkey's foreign minister on Monday warned against any intervention by Syrian pro-government forces alongside Kurdish militias in northern Syria, saying it would not prevent Ankara from continuing its month-old offensive.

Turkey views the YPG as a terrorist offshoot of the outlawed Kurdistan Workers' Party (PKK), blacklisted by Ankara, the United States and the European Union.

"If the regime is entering (Afrin) to oust the PKK, YPG, there is no problem. But if they are entering to protect the YPG, then no one can stop us and Turkish soldiers," Cavusoglu said during a visit to Jordan.

On Monday, SANA said "popular forces will arrive in Afrin within a few hours to support its people's stand against the Turkish regime's attack on the area and its people," citing its correspondent in Aleppo.

Turkish President Recep Tayyip Erdogan has previously threatened to expand the operation to include the YPG-held town of Manbij and other towns leading to the Iraqi border.

The Turkish army, backed by Syrian rebels, has been conducting a ground and air offensive against the region since January 20 to drive out the YPG.

Cavusoglu said the aim of the operation, dubbed "Olive Branch", was aimed at "removing terrorists" from its southern border.

- Putin, Erdogan phone call -

Damascus previously denounced Ankara's "aggression" in Afrin but had never explicitly said it would intervene before Monday.

Syria's Kurds have gradually implemented a self-rule model across much of the country's north, including Afrin, since 2012.

Kurdish fighters and government troops have largely stayed away from each other since then, though there have been short-lived clashes in the cities of Hasakeh and Qamishli in the past.

Last week, YPG chief Sipan Hamo told reporters his forces would have "no problem" with Damascus intervening to help repel Turkey's assault.

A few hours after the SANA report, Erdogan spoke on the phone with Russian President Vladimir Putin and they discussed the "latest developments in Syria, especially in Afrin and Idlib", a Turkish presidential source said.

The issue of establishing new observation posts in Idlib was discussed, the source said.

Turkey, Russia and regime supporter Iran agreed last year to create "de-escalation" zones in four areas including Idlib, where six observation posts have already been set up by Turkish forces to monitor any fighting.

The northwestern province is nearly completely under the control of anti-government forces, predominantly Hayat Tahrir al-Sham (HTS), a group led by Al-Qaeda's former Syria affiliate.

While Turkey has called for the ouster of Syrian President Bashar al-Assad, Russia has provided armed support to the regime and controls the airspace of northern Syria.