Turkey's foreign minister and his Arab counterparts in the Gulf on Thursday condemned "indiscriminate" air strikes on Syria's Aleppo and expressed "deep regret" at the UN's inability to stop the raids.

The concerns came in a statement closing a meeting in the Saudi capital between Ankara's Foreign Minister Mevlut Cavusoglu and his counterparts from the six-nation Gulf Cooperation Council.

Russian and Syrian warplanes are backing a large-scale offensive by Syrian government forces against rebel-controlled east Aleppo.

More than 70 civilians died on Tuesday and Wednesday alone in air strikes and regime artillery fire on eastern Aleppo districts, a monitoring group said.

"Ministers condemned the escalation of military operations in Aleppo by the regime and its supporters through indiscriminate air raids against the civilian population and infrastructure," the GCC-Turkey communique said.

New Zealand, one of 10 non-permanent UN Security Council members, on Wednesday presented a draft resolution demanding an end to air attacks in Aleppo.

The council earlier failed to adopt two resolutions on a ceasefire in Syria, one of which was vetoed by Russia during a stormy meeting at the weekend.

Gulf ministers and their Turkish counterpart "expressed their deep regret for the inability of the UN Security Council to make a decision to stop the air campaign and the bombing of civilians in Aleppo", their statement said.

The foreign ministers of GCC members Saudi Arabia and Qatar, along with Cavusoglu, are to join US Secretary of State John Kerry and Russian Foreign Minister Sergei Lavrov in the Swiss city of Lausanne on Saturday for the latest diplomatic push to settle the conflict.

Despite differences over Syria, Russia and Turkey have been pursuing closer ties.

Ankara has staunchly backed Syria's opposition, as does the GCC, and both see no future for Syria's President Bashar al-Assad.

- Like-minded -

At a news conference, Saudi Foreign Minister Adel al-Jubeir said the Gulf views the Ankara-Moscow rapprochement positively.

"We see the reduction in tension between Turkey and Russia as perhaps an opportunity" that could help a solution in Syria.

"Turkey views the situation in Syria exactly the way we do."

Cavusoglu said a normalisation of ties does not mean Turkey will change its position on Assad, "but having a good dialogue is always better than not".

Ministers expressed concern about the use of "sectarian militia forces" as part of an imminent Iraqi operation to retake that country's Mosul city from the Islamic State group jihadists.

UN human rights chief Zeid Ra'ad Al Hussein has said there was strong evidence of atrocities by the Iran-backed Ketaeb Hezbollah,ok one of the main militias that fought alongside security forces to recapture another Iraqi city, Fallujah, earlier this year.

"If these militia are going to have a role in Mosul then I think this is going to be a catastrophe," Jubeir told reporters.

In their statement, the GCC and Turkey also emphasised the goal of establishing a free trade area "as soon as possible".

Turkey's Economy Minister Nihat Zeybekci attended the Riyadh talks, part of a regular dialogue between the two sides.

Saudi Arabia has become an increasingly close ally of Turkey.

The kingdom's Crown Prince Mohammed bin Nayef met last month in Turkey with President Recep Tayyip Erdogan.

Cavusoglu told reporters that Erdogan "is shortly going to visit Saudi Arabia" but the date has not been finalised.