ISTANBUL (Reuters) - Turkish prosecutors have dropped a corruption case against 53 suspects, among them two former minister's sons, drawing a line under a scandal that dogged now-President Tayyip Erdogan's inner circle for months, media said on Friday.
The scandal posed one of the biggest challenges to Erdogan's 11-year rule as prime minister, leading three members of his cabinet to quit and drawing international criticism for his response - tightening Internet controls and reassigning police, judges and prosecutors.
Istanbul prosecutors ruled that there was no case to answer as evidence had not been collected appropriately, there was no evidence of a crime and no criminal gang was uncovered, broadcaster CNN Turk reported.
Officials from the prosecutors office were not available to comment.
In May a Turkish court lifted a travel ban on one of the suspects, Iranian businessman Reza Zarrab, in what was seen as a sign that the investigation was running out of steam.
Among the other suspects in the case were sons of former Interior Minister Muammer Guler and former Economy Minister Zafer Caglayan.
A police report leaked earlier this year presented Zarrab as the ringleader of a group which allegedly helped Iran to exploit a loophole in the West's sanctions regime that for a time allowed the Islamic Republic to purchase gold with oil and gas revenues.
The report alleged bribes were paid to Turkey's then economy minister, interior minister and European Union affairs minister as well as the chief executive of state-controlled lender Halkbank.
All three ministers, who subsequently resigned or were dropped from the cabinet, denied wrongdoing and were not charged. Halkbank has denied violating any domestic or international laws.
Despite the controversy, Erdogan's ruling AK Party swept to victory in local elections at the end of March that were seen as a referendum on his rule, and prosecutors have dismissed other corruption cases in the affair.
Erdogan subsequently won the country's first direct election for president in August.
He cast the graft probe as an attempted "judicial coup", a plot to unseat him devoid of legal merit and said it had been orchestrated by U.S.-based Islamic preacher Fethullah Gulen, a former ally with influence in the police and judiciary. Gulen denied involvement.
Thousands of police officers and hundreds of members of the judiciary have been reassigned since the scandal, with several prosecutors removed from the corruption case.
(Writing by Daren Butler; Editing by Robin Pomeroy)