Spain's national rail operator is in talks with the tunnel's owner to expand into the London to Paris cross-Channel route.
Renfe's move would pit it against Eurostar, a subsidiary of French state-owned train operator SNCF, which presently has a monopoly on the tunnel route.
Since 1994, Eurostar has maintained a monopoly on passenger transport through the tunnel, but as France's domestic rail industry becomes more competitive, new companies are looking at the route.
Renfe, a state-owned company, said it has begun discussions with Getlink, the company that manages the cross-Channel tunnel, about running high-speed trains through it.
At the moment, there are available slots and capacity to operate on the high-speed line,” Renfe said in a statement.
“This high-speed corridor has high traffic and was growing until Covid-19 – a trend that is set to recover next year. According to demand analysis, it would be viable and profitable for Renfe to compete with Eurostar.”