The SNCF French railway company said Monday it would offer reduced fares and 80,000 extra seats between Paris and London this week to help air passengers grounded by the volcanic ash cloud.
"We will have 80,000 extra seats between Paris and London this week and on top of that we will offer them for 89 pounds (100 euros)", Guillaume Pepy, chief executive officer of the state-owned firm, told Europe 1 radio.
Last week, a round-trip ticket between London and Paris cost 245 euros.
Pepy also said SNCF would offer a "symbolic fare of 50 euros" to French travellers stranded in regional airports to get them home by train while Air France jets are grounded.
Flights over Europe have been banned or restricted for five days, due to a vast cloud of ash drifting south from Iceland's Eyjafjoell volcano, which experts fear could endanger airliners.