(Adds details, opposition reaction)
PARIS, Aug 31 (Reuters) - French President Francois Hollande reaffirmed to U.S. President Barack Obama on Saturday his will to punish Syria for a suspected chemicals weapons attack but was under increasing pressure to put the intervention to parliament.
Obama and Hollande spoke by telephone before Obama's statement that he would seek authorisation from Congress before any strike.
"The president reaffirmed to him his determination to act to sanction the regime," a source close to Hollande said. "Each country's pace of action must above all be respected. It's important for the Americans to have the green light from Congress."
However, pressure was now mounting on Hollande to also seek formal approval from parliament, which is due to hold a non-voting debate on Syria on Sept. 4.
"Like the U.S. president, who decided to consult the U.S. Congress in the name of democratic principles, the French president must organise, after the debate, a formal vote in parliament," Jean-Louis Borloo, the head of French opposition party UDI, said in a statement.
A BVA poll on Saturday showed most French people did not want France to take part in military action on Syria and most did not trust Hollande to do so.
Hollande, whose popularity has been hurt by economic gloom, showed unexpected military mettle when he dispatched troops to help Mali's government fend off Islamist rebels earlier this year, an intervention backed by two-thirds of the public.
(Reporting by Julien Ponthus and Dominique Vidalon; Writing by Catherine Bremer and Dominique Vidalon; Editing by Alison Williams)