Ofcom confirmed six companies will take part in an upcoming spectrum auction for bands earmarked for 5G in the UK, after the final deadline for withdrawal elapsed.

The parent companies of existing operators EE, O2 UK, Vodafone UK and 3 UK will be joined by regional wireless broadband provider Connexin and Airspan Spectrum Holdings – a venture backed by Japanese conglomerate SoftBank – in the auction process.

Bidders will compete for 40MHz of spectrum in the 2.3GHz band – available for LTE use – and 150MHz of 3.4GHz spectrum intended to support the country’s 5G service.

Ofcom said it planned to press ahead with the auction “as quickly as possible” with the next stage set to start later this month, after it fought off legal challenges from 3 and EE.

Both operators disputed the regulator’s auction rules late in 2017 with 3 claiming spectrum caps imposed on operators did not do enough to address competition concerns, while EE wanted the cap removed completely.

Courts ruled in Ofcom’s favour in December 2017 and although EE accepted the decision, 3 took its case to appeal. The appeal was finally rejected in February.

Ofcom chief executive Sharon White slammed the action for delaying the auction for commercial interests.

Announcing the identity of the qualified bidders, Ofcom spectrum director Philip Marnick said: “We’re pressing ahead with the auction to make these airwaves available as quickly as possible. This will benefit today’s mobile users by providing more capacity for mobile broadband use. It will also pave the way for 5G – allowing operators to launch the next generation of mobile technology.”