Telefónica revealed it has “initiated” plans to float its mobile network O2 as the Spanish telecoms giant also revealed it will list its infrastructure business by the end of the year, after it failed to offload its UK network.

The Spanish group was denied a £10.25bn payday earlier this year when attempts to merge O2 with rival network Three, owned by Hong Kong-based conglomerate CK Hutchison, were blocked by Europe’s competition authorities.

Telefonica now says preparations for an initial public offering of O2 UK are underway, in which it will keep a majority share in the mobile network, which is run by chief executive Mark Evans, who took over from Ronan Dunne last month.

Telefónica, which is struggling to contend with its €50bn debt pile, will also list its infrastructure business Telxius, which owns mobile masts and fibre-optic cables, on the Barcelona, Bilbao, Madrid and Valencia stock exchanges before 2017, also planning to keep a majority stake in the business.

Telefónica set up infrastructure arm Telxius as a new company in February. It is controlled by boss Alberto Horcajo, the former financial chief at Telefónica Brazil.

It sells wholesale access to its 15,000 telecoms towers in Spain and to its 31,000km of submarine fibre-optic cables that connect Europe to the US and South America.

Plans to float off its British business O2 had been on hold until after the referendum following the collapsed sale to Three's Hutchison last May.