* Juppe says it will seek stronger resolution if plan fails
* France hopes Russian position will evolve
* New Syrian opposition group to form in Paris on Thursday (Adds creation of new Syrian opposition group)
By John Irish
PARIS, April 25 (Reuters) - France wants to see 300 U.N. observers in Syria within two weeks and will push for a "Chapter 7" resolution at the United Nations unless Damascus complies with the terms of a peace plan by early May, Foreign Minister Alain Juppe said on Wednesday.
Chapter 7 of the U.N. charter allows the Security Council to authorise actions which can ultimately include the use of military force.
Speaking to reporters after meeting opponents of Syrian President Bashar al-Assad, Juppe said there had to be a rapid deployment of observers as the plan was "extremely compromised".
"This cannot continue indefinitely. We want to see observers in sufficient numbers, at least 300 ... deployed as quickly as possible," Juppe said, adding that he wanted them in Syria within "two weeks not three months".
U.N. peacekeeping chief Herve Ladsous has said it will take a month to deploy the first 100 monitors.
Juppe said it was "unacceptable" for Damascus to try to dictate which nationalities could take part in the mission.
International envoy Kofi Annan said on Tuesday Syria had failed to comply with a pledge to withdraw weapons from population centers, and towns where citizens met U.N. truce monitors may have been attacked.
Juppe said that May 5, when Annan presents a report to the Security Council on Syria, would be the "moment of truth".
"If that does not work, we cannot allow the regime to defy us. We would have to move to a new stage with a Chapter 7 resolution at the United Nations to take a new step to stop this tragedy," Juppe said.
The French government of President Nicolas Sarkozy, who faces the second round of a tough re-election battle on May 6, has long led calls for Assad to step aside.
It has also said it would support military action if there was a U.N. mandate, something that remains unlikely given Moscow and Beijing's opposition to intervention.
When asked if he thought Russia would support a Chapter 7 resolution, Juppe said Moscow had already accepted resolutions enabling Annan's mission and the sending of observers.
"I hope they will realise that the regime is blocking the process and I hope that their position will evolve in light of what's happening on the ground," he said.
Juppe met several opposition Syrians on Wednesday, including Rima Flihan, a writer and activist, who fled Syria in September, human rights activist Suhayr Atassi and Alawite writer Samar Yazbek.
Paris has given diplomatic backing to the opposition Syrian National Council (SNC), but has also urged it to do more to appeal to Syria's minority Christians and Alawite Muslims.
Another group of opponents to Assad, comprising members of Syria's civil society and the Free Syrian Army, are set to unveil a National Transitional Government in Paris on Thursday.
Its Saudi-based spokesman Nofal al-Dawalibi told Reuters the SNC had failed to represent Syrians and made it harder for the international community to support the opposition.
"Our point of view is that we can't unify the opposition in Syria because we don't have the regulations, laws or land where we can all meet to discuss these matters, so it's impossible to have a legislative body, so we are creating an executive body."
He said the "government" would be made up of 35 people inside Syria and five or six on the outside who would provide finance, weapons, humanitarian aid and coordination.
Dawalibi said his group had spoken to French, U.S. and Gulf Arab officials, although declined to say whether Saudi Arabia was backing his organisation. (Reporting By John Irish; editing by Daniel Flynn)