ISTANBUL: Turkey and the United States played down differences in the fight against Islamic State on Friday, but Prime Minister Ahmet Davutoglu made clear Ankara would keep pressing for a no-fly zone in Syria and President Bashar al-Assad's removal.

Turkey has been a reluctant partner in the US-led coalition against the Islamic State (IS) insurgents. Ankara argues that the coalition's air strikes in Iraq and Syria are not enough and it has pushed for a more comprehensive strategy involving Assad's departure and the creation of a buffer zone inside Syria to protect displaced civilians.

Ankara has in turn drawn criticism for letting thousands of foreign rebels cross its borders and for doing little to end the IS siege of the Syrian border town of Kobani, a battle that has raged for months within sight of Turkish military positions.

“We've been friends for a long time and one of the great advantages of being back in Turkey with a friend and Nato ally is we're always direct with one another,” US Vice President Joe Biden told a joint news conference with Davutoglu.

“We have tackled a number of very contentious issues regionally and internationally and we've always eventually come out on the same side,” he said.

Speaking just before Biden's arrival in Istanbul, Davutoglu, who has spent the last two days in Iraq, said there could be no sustainable peace in Syria while Assad remained in power.

“Look at how things are getting better in Iraq after a government chosen by the people is in place,” he told reporters at Istanbul airport.

“But in Syria, you can't bring peace trying to destroy a terrorist organisation on one side of the country, while a regime in Damascus is using all sorts of weapons to exterminate a portion of its own people on the other.”

Biden will discuss Turkey's role in the coalition with Davutoglu and President Tayyip Erdogan. Their talks are also expected to focus on Turkish efforts to stop the flow of foreign jihadists joining Islamic State via Turkey, and Ankara's assistance to the more than 1.6 million refugees on its soil.

Davutoglu said that while Turkey and Washington may differ in their methods, they had common aims, with the United States also wanting to see Assad gone.