The government previously said it would encourage a fourth entrant to increase competition with the largest operator Proximus, Orange Belgium and Telenet's BASE.

"Five mobile operators applied for the future auction and all were declared eligible after examination," industry regulator IBPT-BIPT said in a statement, adding that the auction would define Belgium's mobile landscape for the next 20 years.

It did not name the operators. The auction will cover the new main 5G licences and existing 2G and 3G spectrum.

The country's plans for a 5G auction were blocked for years by disagreements between federal and regional governments.

(Reporting by Marine Strauss @StraussMarine, editing by Philip Blenkinsop, Kirsten Donovan)

By Marine Strauss