For more than 25 years, French majority-owned Eurostar has had a monopoly on running trains through the tunnel. Renfe – a rival to Eurostar – wants to exploit the slots available through the tunnel to operate a high-speed train service. It says it has seven trains ready to operate on the line which its bosses say they could make profitable within four years.

Renfe said it has support from HS1 – the British infrastructure group which owns and manages track and stations between London and the tunnel – and Channel Tunnel operator Getlink.

The move is seen as a continuation of a tit-for-tat spat continuing between Renfe and French rail operator SNCF (the majority shareholder in Eurostar) following the latter’s launch of rail services in Spain earlier this year.

Britain’s stake in Eurostar was sold in 2015 for £750m (US$1.03bn) by the then prime minister, David Cameron, after which SNCF became the majority owner. When the British government refused to provide a bail-out earlier this year, Eurostar came very close to collapse. Following a last minute rescue deal between lenders and shareholders, it is said to be planning a merger later this year with Belgian high-speed operator Thales.