By Graham Keeley and Horaci Garcia
BARCELONA (Reuters) -Thousands of Catalan independence supporters took to the streets of central Barcelona on Monday in a march to mark the Spanish region's National Day, just as separatist parties take centre stage in efforts to form a national government.
Marchers carried red, yellow and blue "Estelada" flags and chanted slogans demanding Catalonia's secession from Spain, packing into the Plaça d'Espanya square to hear speeches from leaders of the pro-independence movement.
However, Reuters journalists said turnout at this year's La Diada events, as the National Day is known, was relatively low compared to past ones.
Police pegged it at 115,000 people, while the march's organisers said 800,000 took part. Attendance has waned in recent years as support for breaking away from Spain has decreased.
But the two main Catalan parties are now in the middle of negotiations with Acting Prime Minister Pedro Sanchez and his allies on forming a new Spanish government, and hope the talks may boost the flagging independence cause ahead of regional elections in 2025.
"Whatever political agreement we reach, whatever we propose, will be to move closer to the goal of every nation, which is to be a free and independent state," Jordi Turull, general secretary of the Junts per Catalunya party, said at a Diada event on Monday prior to the main demonstration in the evening.
Imma Caboti, a Catalan living in the United States who had returned to Barcelona for La Diada, said Catalonia's separatist parties should continue to press for independence.
"We understand the politics is about trading and giving, but we don't want them to give up this opportunity and we want them to stand firm," she told Reuters.
To form a government following an inconclusive election in July, Sanchez, of the Socialist Party, would need the seven lawmakers of the conservative Junts and the seven votes from the more moderate Esquerra Republicana de Catalunya (ERC).
Junts leader Carlos Puigdemont, who lives in self-imposed exile in Belgium as he is wanted in Spain for spearheading a failed secession bid in 2017, last week insisted on an amnesty for pro-independence leaders as a condition for talks.
Puigdemont laid out tough conditions for his party's support in parliament for Sanchez to stay in power.
He called for Spain to abandon judicial actions against separatists, although he stopped short of demanding a new vote on independence.
His rival at the ERC, Pere Aragones, on Sunday went a step further, demanding a referendum.
"An amnesty alone will not resolve the sovereignty conflict with the state. Catalonia wants a free vote on independence," Aragones, who is president of the region, said in Barcelona.
Alberto Nunez Feijoo, whose conservative People's Party (PP) won the most votes in the July 23 election, will take the first stab at a vote to form a government on Sept. 27, but his chances are seen as slim since his party opposes any concessions to separatists.
Support for Catalan independence has slipped since 2017, when a referendum which was ruled illegal by a court brought on Spain's worst political crisis in decades.
A survey published by the Catalan Centre for Public Opinion (CEO), operated by the regional government, in July found 52% opposed splitting from Spain while 42% supported independence.
Still, Jordi Vilanova Karlson, an activist running a promotional stall, said the stalemate in the Spanish parliament represented an opportunity for Catalonia's independence movement.
"What we want is to move forward towards a referendum... where the Catalan people can actually decide once and for all," he said. "We should be governing ourselves."
(Reporting by Graham Keeley, Inti Landauro and Corina Pons; Additional reporting by Albert Gea; Writing by Charlie Devereux; Editing by Angus MacSwan and David Latona)
