US Secretary of State Rex Tillerson has described Turkey as a trusted ally after meeting its leaders in Ankara.

His visit comes amid worsening relations between the two Nato allies.

Speaking after meeting his Turkish counterpart Mevlut Cavusoglu, Mr Tillerson said the US wanted strong links between the two countries.

They are at odds over US backing for Kurdish fighters in Syria and Turkish demands for Washington to extradite anti-government cleric Fethullah Gulen.

"In the United States, the people of Turkey have a trusted ally and a partner who is committed to its safety and security, and advancing economic opportunity," Mr

"We look forward to approaching these challenges together, and the Trump administration will continue to build ties with this long-standing ally and our friend."

Mr Tillerson said Turkey was an important ally of the US in the battle against the group known as Islamic State (IS) and the two countries agreed on the importance of lessening the disruptive influence of Iran in the Middle East.

The secretary of state's visit comes amid continuing tensions within Nato and as Turkey angrily criticised the arrest of a leading Turkish banker in the US.

Mehmet Hakan Atilla, a top official of the state-owned Halkbank, was detained on Tuesday on charges of helping Iran evade US sanctions.

Turkish Justice Minister Bekir Bozdag said the case was designed to tarnish President Recep Tayyip Erdogan.

Mr Tillerson is the most senior US official to travel to Turkey since President Donald Trump was sworn in in January.

Mr Tillerson's visit comes as Turkey announced that it had "successfully" ended its seven-month Euphrates Shield military campaign in northern Syria.

One of Turkey's main grievances with the US is the policy started by the Obama administration of supporting Kurdish fighters in Syria who are fighting IS forces.

Turkey views the Syrian Kurdish People's Protection Units (YPG) as a "terror group" linked to Kurdish separatists waging an insurgency inside Turkey since 1984.

The two sides are also at loggerheads over Fethullah Gulen. Mr Cavusoglu said that he expected Washington to take "concrete steps" to extradite him.

Turkey accuses the cleric of orchestrating last July's failed coup.

Officially the US insists any decision on returning him to Turkey remains a judicial - rather than a political - decision.