A supreme court ruling has prompted Turkish telecommunications company Turkcell to drop its US$4,2bn lawsuit against MTN Group.

Turkcell filed the lawsuit in the US last year claiming MTN conspired with and bribed Iranian officials to win a licence in Iran that had originally been awarded to the Turkish mobile operator.

Turkcell also alleged that MTN used it influence in the South African government to secure the supply of defence equipment to Iran and to support its nuclear development programme at meetings of the International Atomic Energy Agency.

The case was filed originally in a US district court because both companies had business dealings in the US and because Turkcell alleged MTN had “breached rules of international law”.

Last October, the court postponed the case in order to await the outcome of a case before the US supreme court concerning a human rights law, first enacted in 1789, called the Alien Tort Statute. The statute forms the basis of Turkcell’s suit.

The statute allows US courts to hear human rights cases brought by foreigners for actions outside the US. Last month, the US high court opted to limit the ability of foreign plaintiffs to invoke the statute in instances where there is not a strong US connection to the incident.

On Wednesday, lawyers for Turkcell filed to have the case dismissed in light of the ruling.

Although MTN professed its innocence throughout proceedings, it launched an independent, year-long investigation into the allegations, the Hoffmann Committee, which cleared MTN of wrongdoing and labelled Turkcell’s accusations a “fabric of lies, distortions and inventions”.