The move would pit the state-owned company against Eurostar which has been running the same route since the high-speed line opened in 1994.
It was first reported in Spanish paper El Pais and later confirmed by the company, which said: “Renfe wants to operate on the Paris-London high-speed line through the Eurotunnel, and has already started initial contacts to compete with Eurostar.
“At the moment there are available paths and capacity to operate on the High Speed line”
Such a move would raise the possibility that longer-distance services could in the future be opened between the UK and the likes of Madrid and Barcelona.
“In a second phase, the service could be extended to new French and international destinations,” the company said.
The high-speed line connects the British and French capitals in two hours and 15 minutes.
Before the pandemic, it was used by nine million passengers annually but Eurostar train traffic fell sharply when Covid hit.
Renfe’s proposal would see it operate at least seven of its own trains, which would need to be approved for use through the Channel Tunnel
The tunnel’s operator, Getlink, said: “The tunnel has always offered open access to rail operators and provides an attractive and low-carbon route for travel and trade.”