The UAE's telecoms regulator has ordered an investigation into Du's claims surrounding its plans to run a fourth-generation (4G) network.
The Telecommunications Regulatory Authority (TRA) said on Friday that it has instructed du "to suspend and modify its declaration to run the 4G network", according to state news agency WAM.
It said the TRA had requested information from Du so it could "study its compatibility with the regulatory framework of the TRA, the approvals of services delivery and the granted licence", without elaborating.
The announcement comes as Etisalat on Sunday reportedly filed a complaint to the TRA urging it to take action after du released a statement claiming its commercial service, HSPA+ falls under 4G services.
Du said in a statement: "As a part of a series of announcements and public communication on the eve of GITEX 2011, Du released an advertisement of its Fastest Nationwide 4G Mobile Data Network.
"The reference to 4G in that advertisement is to our HSPA+ network. This is based on the International Telecommunications Union’s 2010 determination, issued vide their official press release. Other international operators in highly regulated markets also refer to their HSPA+ networks as 4G."
It added: "We have received a communication from the TRA stating that the TRA would like to consider what is implied by the reference to 4G in the Du advertisement and whether the advertisement implies that Du has deployed technology that would require additional licensing.
The TRA instructed Du to suspend the above advertisement until such time that the TRA and Du have discussed the matter further and agreed whether or not additional licensing is required."
Du said it would comply with the instructions of the TRA and looked forward to discussing the matter further with them.
Du in August said its second quarter profits had increased 52% while net income grew from AED207.2 million ($56.4m) from AED137.4m a year earlier.
Etisalat, who last week said it planned to roll out 4G services by the end of the year, has previously claimed to be the first to offer a fourth generation service.
Fourth generation networks will be able to deliver high speed data downloads including high definition (HD) broadband and mobile TV services.