The Spanish government says it will return thousands of official documents to the autonomous region of Catalonia that were seized after the civil war.
Republican leftists lost Spain's civil war to Franco's right-wing forces
More than 300,000 files and 1,000 photographs were taken by Francisco Franco's nationalist forces in 1940.
Catalonian officials have campaigned for the return of the documents for more than 20 years.
The opposition has criticised the government, saying the country's archives should stay together.
"A self-respecting country should defend the unity of its identity, its archives and its museums," conservative Popular Party spokesman Eduardo Zaplana said.
The documents were stored in a military library in the north-western city of Salamanca, following Spain's 1936-39 civil war, won by Franco's forces.
They include personal letters, files and a record of anti-Franco propaganda that were compiled by Catalan unions, political parties and regional government authorities.
The government said the decision to propose a law to return the papers would repair a historic wrong.
"This will put an end to an illegitimate state of affairs," Deputy Prime Minister Maria Teresa Fernandez de la Vega was quoted as saying by Reuters news agency.