The arrest in the United States of a top Turkish banker charged with participating in a multi-year scheme to violate sanctions against Iran is a "completely political" move, Turkish Justice Minister Bekir Bozdag said on Thursday.

The Halkbank executive is accused of conspiring with Turkish-Iranian gold trader Reza Zarrab, who is already on trial. Bozdag said there was no evidence incriminating Zarrab or Turkey.

The arrest escalates a case that has fuelled tension between the United States and Turkey. President Tayyip Erdogan has said he believed U.S. authorities had "ulterior motives" in prosecuting Zarrab, who was arrested in March 2016 in Miami.

"There is nothing legally sound there and Turkey is facing a completely political plot," Bozdag told broadcaster A Haber. "It aims to tarnish the Turkish state, government and president."

Shares of Halkbank, Turkey's fifth-largest listed bank by assets, endured their biggest one-day fall on Wednesday, falling 14 percent after Deputy General Manager Mehmet Hakan Atilla was charged. They rose 0.7 percent on Thursday.

Atilla is accused of conspiring with Zarrab to conduct hundreds of millions of dollars of illegal transactions through U.S. banks on behalf of Iran's government and other entities in that country.

U.S. Secretary of State Rex Tillerson is visiting Ankara on Thursday and will hold talks with Erdogan and other Turkish officials.