(Adds new parliament president comments)
By Elizabeth Pineau and Ingrid Melander
PARIS, June 28 (Reuters) - France's most fragmented parliament in decades sat for the first time on Tuesday, as President Emmanuel Macron faced the prospect of having to negotiate each reform with opposition parties who will be looking to flex their newly won influence.
Macron, who was re-elected president in April, lost control of parliament in legislative elections this month - meaning it is no longer a rubber stamp for the government's plans.
With no tradition of coalitions or minority government, unlike most of France's European neighbours, the most likely scenario is, for now, case-by-case negotiations on reforms, after opposition groups rejected any prospect of a deal.
In her first speech to the National Assembly, its new president Yael Braun-Pivet - a former lawyer from Macron's party and the French parliament's first female chair - alluded to the need for compromise with opposition parties.
"French people are calling on us to work together, to debate rather than to do battle," Braun-Pivet said.
Macron party stalwarts said they were ready to embrace a new style of governance.
"We will have to be able to build majorities text by text, case by case, beyond partisan divisions," Pieyre-Alexandre Anglade, from Macron's centrist Renaissance party told Reuters as lawmakers started gathering in the National Assembly.
"Most European countries manage to work beyond divisions, either through compromises or through coalitions ... There is no reason we couldn't do that in France."
Opposition lawmakers made clear they would not roll over easily.
"The previous ... term, which was that of an all-powerful government and a parliament that just rubber-stamped things, is over," said Adrien Quatennens, of the hard-left La France Insoumise.
Socialist MP Boris Vallaud said it was up to the government to do things differently than in the past and take the opposition's proposals on board, if it wants reforms to be adopted.
"We've made proposals on the cost of living. Are they ready to back them?" he told Reuters.
The first session was chaired, as per tradition, by the assembly's eldest member who, for the first time, was a far-right lawmaker, 79-year old Jose Gonzalez from Marine Le Pen's National Rally.
"We hope to work with the governement in a constructive way," he said.
A first test of the new parliament's taste for compromise will come on Thursday, when lawmakers must decide who will chair the assembly's finance committee, its most powerful panel, tasked with controling state accounts.
The role traditionally goes to the biggest opposition group, which both the National Rally (RN) and the left-wing Nupes alliance say they are. The RN is the biggest single opposition party, while Nupes are the biggest alliance. (Reporting by Elizabeth Pineau; Writing by Ingrid Melander; Editing by Alison Williams and Emelia Sithole-Matarise)