Chief Executive of South African telecom MTN Group, Sifiso Dabengwa on Thursday hailed a U.S. Supreme Court ruling as a major boost to its defense against a $4.2 billion lawsuit from rival Turkcell.

"It's definitely a positive for our case," Sifiso Dabengwa told Reuters in a telephone interview on Thursday.

Turkcell is suing MTN, Africa's biggest mobile phone company, in a U.S. federal court using a 224-year-old law.

However, the U.S. Supreme Court on Wednesday limited the ability of human rights plaintiffs to invoke that law, a ruling seen as a major victory for foreign multinationals.

The federal court had delayed ruling on the Turkcell suit filed a year ago, pending the outcome of Wednesday's Supreme Court ruling.

Critically for Turkcell's suit - which involves two companies that are not based in the United States - the ruling is seen as limiting the reach of U.S. courts in claims seen as lacking sufficient connection to the United States.

Turkcell said in a statement it was "inappropriate" to comment before a ruling from the federal court, adding that its case could be addressed in the coming weeks.

Turkey's largest cell phone firm alleges that MTN used bribery and peddling of political influence to win a mobile license in Iran that was first awarded to Turkcell.

MTN has denied the charges.

Shares of MTN were up 0.81 percent at 163.51 rand at 1105 GMT. Turkcell's shares were also little changed.