Africa's largest telecom operator, MTN, may have been cleared of corruption allegations in its dealings in Iran by a committee of investigators, but the case may nevertheless affect the company's expansion plans in Africa and the Middle East until the matter is fully concluded, as most African countries are now embracing a zero-tolerance approach to corruption.

A report by a committee of investigators appointed by MTN itself and chaired by retired British judge Leonard Hoffmann last week dismissed allegations by Turkcell that MTN became involved in corrupt practices as it pursued a GSM license in Iran as a "fabric of lies, distortions and invention."

But a related lawsuit brought by Turkcell is pending in the U.S. District Court for the District of Columbia, and this puts MTN in a position that may affect its reputation and its expansion drive. The U.S. case is currently on hold, pending a U.S. Supreme Court ruling.

Meanwhile, following the Hoffmann committee's report, MTN has sought to reassure shareholders and by extension governments in Africa that it was clean in its dealings.

"Hoffmann concluded that he found nothing in the conduct of MTN over this period that puts at question MTN's integrity or propriety. This is a reassuring validation of MTN's culture and ethical business practices," said MTN chairman Cyril Ramaphosa in a statement.

The Istanbul-based Turkcell alleges that in 2004, MTN improperly paid bribes to South African and Iranian government officials to win the telecom license in 2005. The license had initially been awarded to Turkcell by the Iranian authorities after a tender in 2003. Turkcell was, however, stopped from securing the license and MTN, which had originally submitted a runner-up bid, secured it.

Turkcell also accused MTN of promising Iran that MTN could deliver South Africa's vote at the International Atomic Energy Agency (IAEA) in support of the country's controversial nuclear program in exchange for the GSM license.

Turkcell's allegations come against the backdrop of the U.S. and Europe's forceful economic sanctions designed to deter Iran from pursuing its nuclear development program.

The alleged corrupt practices in Iran by MTN led Turkcell to file a lawsuit in the U.S. court against the South African operator, claiming not less than US$4.2 billion in damages, plus interest.

Turkcell said it decided to file the lawsuit in the U.S. against MTN because both companies have extensive business dealings in the U.S. and because of the allegations that MTN breached international law. The Iranian unit is MTN's fastest-growing affiliate, with more than 34 million subscribers. MTN has a 49 percent share in Irancell, owned and controlled by the Iran Electronic Development Co.

Backed by a collection of alleged MTN internal documents including emails, invoices, memos and presentations, Turkcell accuses MTN of a "staggeringly brazen orchestra of corruption."

Turkcell has said that the U.S.' Alien Tort Statute gives district courts jurisdiction over cases related to violations of international law, and therefore allows its case to be heard in the U.S. But U.S. District Judge Reggie Walton, who is presiding over the Turkcell suit in the U.S., has said the jurisdiction issue may be decided by the Supreme Court, which heard arguments in a case involving the Alien Tort Statute in October, and is slated to make a ruling in its current session.

The statute is usually invoked in cases of human rights abuses. The Supreme Court case involves allegations by a group of Nigerians who allege that Royal Dutch Shell officials based outside the U.S. helped Nigeria commit torture and murder more than a decade ago.

MTN insists it was not the cause of Turkcell losing the license in Iran. The company said Turkcell's own "failures to meet Iranian legal and commercial requirements" caused its ouster from the license process.

MTN engaged Hoffmann in February 2012 in a bid to resolve the matter. Turkcell refused to cooperate with Hoffmann's investigations.

"The committee's finding is certainly welcome but we should not forget that it was appointed by MTN, a company facing the accusations," said Edith Mwale, a telecom analyst at African Center for ICT Development.

She said although the committee may have operated independent of MTN influence, its report still raises doubts because the impartiality of the committee is certainly questionable.