South Africa’s telecoms regulator said on Friday it will challenge a court application by MTN Group seeking to review or scrap the regulator’s auction process for awarding spectrum vital for rolling out 5G technology.

MTN is the latest mobile operator to take the Independent Communications Authority of South Africa (ICASA) to court. Smaller rival Telkom went to court in December to halt the sale, a move ICASA says it will also challenge.

Operators have been waiting more than a decade for ICASA to release new spectrum licences seen as vital to attract new investment and help lower costs for operators and users.

The latest legal disputes threaten to further delay the auction, set for the end of March, after similar disputes halted the sale in 2016.

ICASA said it was unfortunate that MTN chose to pursue legal proceedings after it had been in constant communication with the mobile operator to resolve the issues raised.

MTN is challenging ICASA’s decision to put operators in two categories, putting MTN and rival Vodacom in Tier 1 and Telkom, Cell C and others in Tier 2, according to court papers filed on Wednesday and seen by Reuters.

Under this classification, MTN says Tier 1 operators would be excluded from an opt-in auction round, undermining their ability to secure access to the 3.5GHz radio frequency spectrum band seen as vital to their rollout of 5G technology.

ICASA Chairperson Keabetswe Modimoeng said in a statement the latest litigation attempt “is characteristic of either impatience or a subtle desire to channel the Authority’s decision-making outlook”.

“We believe that this licensing process has been balanced, with no room for a winner-takes-all attitude. The process cannot be tailored for the narrow fulfilment of one or two specific mobile operators,” Modimoeng said.

ICASA said the auction will continue as planned unless there is a court order issued to delay or halt the process.