Guillaume Pepy said that the move, which would take up to two years to implement, would create a single and more efficient European railway company and allow travellers simpler and more efficient journeys.
He told reporters that the two networks, which are majority owned by the SNCF, had a total potential to transport 30 million passengers a year compared with 18.5 million in 2018.
The project for the merger, dubbed “Greenspeed”, would have to be approved by the other shareholders of both railway firms and their supervisory boards.
“The idea is to develop and expand the network,” Pepy told reporters in Paris, adding that “SNCF clearly wants to keep control” over the merged entity.
SNCF has a majority 55 percent stake in Eurostar, which runs trains from Amsterdam, Paris and Brussels to London through the Channel Tunnel.
The other investors in Eurostar are the Canadian institutional investor La Caisse de depot et placement du Quebec (CDPQ) with 30 percent, British fund Hermes Infrastructure with 10 percent while Belgian railway operator SNCB has five percent.
Thalys is owned 60 percent by SNCF with SNCB holding a 40 percent stake.
The brand name and the headquarters of the proposed new company have yet to be determined.
“Our aim is to create a European company that can ease the transport from city to city between the countries and can compete with the plane and the car,” said Rachel Picard, the head of SNCF's passenger arm SNCF Voyages.