Vodafone Qatar had long argued Qtel's launch of Virgin-branded pre-paid services constituted a third service provider in Qatar and so violated the terms of Vodafone's license.

"Vodafone Qatar welcomes the news of ictQATAR's decision," said a Vodafone Qatar spokeswoman.

ictQATAR "has instructed Qtel to close all Qtel Virgin Mobile-branded services in Qatar," the regulator, also known as The Supreme Council of Information and Communication Technology, said in a statement.

In a separate statement, Qtel said it would comply with the ruling and will transfer its existing Virgin Mobile customers to Qtel-branded services. These customers will retain their existing balances and phone numbers, but will require a new Qtel SIM card. Virgin accounts must be deactivated by Aug. 4.

Shares of Vodafone Qatar rose 4 percent on the Qatar bourse. Qtel shares gained 1.4 percent.

Distributors and agents returning unused recharge cards will receive refunds, as will customers who do not to switch to Qtel.

In May 2010, Virgin Group signed a partnership deal with Qtel to launch Virgin Mobile Qatar.

"It's a marginal victory for Vodafone Qatar, and a marginal loss for Qtel — it's a small market, and Qtel is still making good returns in that market," said Martin Mabbutt, telecom analyst at Nomura based in London.

"Qtel thought a new brand would help address a lower-spending customer that Vodafone was targeting. It shows the regulator is not prepared to allow them to bend the rules, but there are lots of grey areas in telecom regulation."

The ruling marks the latest spat between the two Qatar operators. Last week, the regulator rejected a claim from Vodafone Qatar that Qtel priced international calls at below costs in what could have amounted to anti-competitive behavior.

Vodafone Qatar has built up a 27 percent share of Qatar's consumer mobile market since launching services in July 2009, according to its financial results for the year ending March 31, while 45 percent of Qatar's population use the firm's services.