PARIS - A full service was restored on the Paris Metro and most French trains were running on Saturday after transport workers ended a crippling strike so that talks on pension reform could run their course.

The nine-day walkout over President Nicolas Sarkozy's plan to end a system of special pension rights has been the biggest challenge yet of his presidency, testing his credibility in keeping an election promise of sweeping economic reforms.

Talks between employers, workers and the state over the specifics of the pension reform plan are due to last a month. Union leaders have said the negotiations must lead to concrete results and hardliners have warned strikes could resume.

"There is much to work with on the agenda of the talks. Now we will see what it will lead to concretely because workers are expecting concrete things," Jean-Claude Mailly, head of the Force Ouvriere union, told Europe 1 radio.

"The fact that there has been a strike means that there has been a whole series of points that they have not obtained and that are on the calendar of negotiations," he added.

Train services have been improving steadily since Thursday, when most union members on strike voted to end their walkout.

Sarkozy has refused to back down on the main element of his reform -- ending early retirement rights for most workers who have them -- and index-linking their pensions to inflation rather than salaries.

However, he has indicated he is ready to make concessions in other areas, such as pay, and French media have reported that an eventual deal might cost the SNCF railways alone 100 million euros ($150 million) a year in salary hikes and perks.

The fact that unions agreed to discuss scrapping special pension rights in the transport and energy sectors is a first, and in stark contrast to 1995 when a previous reform was withdrawn after a massive strike.

State rail operator SNCF said its high-speed TGV lines were running normally or almost normally but only its international night trains would be running on Saturday night. Regional train services had improved but were still disrupted, it said.

In Paris, public transport authority RATP said traffic had returned to normal on the underground Metro network as well as bus and tram lines.

Public opinion has been on the government's side in the dispute, but widespread worries over the cost of living have put pressure on it to stop the dispute escalating.

An IFOP poll for regional newspaper Ouest France published on Saturday found 65 percent of respondents felt their purchasing power had fallen over the past 12 months, compared with 59 percent when asked the same question in January.