Turkey's President Recep Tayyip Erdogan on Friday slammed the conviction in the US of a top Turkish banker in a trial on Iran sanctions busting, saying it was part of a "chain" of plots against his nation.

"What we are seeing in America is a chain of serious plots," Erdogan told reporters at Istanbul airport after the conviction of Mehmet Hakan Atilla, deputy chief executive of Turkish lender Halkbank. 

"If this is the US understanding of justice then the world is doomed. There can be no such understanding of justice."