The sale of a majority stake in Vodafone Egypt to Saudi telecoms operator STC must be approved by the National Telecom Regulatory Authority (NTRA), the country's telecoms regular said on Thursday.

Vodafone Group and STC announced on Wednesday they had signed a preliminary deal to sell a 55 percent stake in the Egyptian unit to Saudi Arabia’s largest telecoms operator STC for $2.39 billion.

The authority said once the deal is finalised, the British-based company must obtain a prior written consent from it ahead of conducting any change in its legal structure or shareholding.

"The completion of the agreement between the two sides is conditional upon presenting it to the authority for final approval to complete the sale," NTRA said.

The approval is meant to "ensure the quality of services provided to telecom users and ensure the state's right," the authority added, stressing that it does not interfere in commercial transactions under free market rules.

The agency said it "has the right to take all the necessary measures to protect national security and public interest while considering competition and protecting users."

The non-binding deal, which values Vodafone at $4.4 billion, is expected to close in June, Vodafone said on Wednesday.

Vodafone Egypt, which started operating in Egypt in 1998, formerly under the name Click GSM, said the sale comes in line with the global company's strategy to focus its operations on Europe and Sub-Saharan Africa.

Vodafone is Egypt's biggest cellphone operator, with more than 40 million subscribers. State-owned landline provider Telecom Egypt owns the remaining 45 percent stake in Vodafone. It said earlier this week it had no intention to sell its share.