MADRID - Opponents of Spanish Prime Minister Pedro Sanchez accused him of putting his party before his country after he announced the reform of a law that is set to benefit leaders of the Catalan independence movement.

Sanchez on Thursday evening announced a proposal to change the law of sedition, which was applied in 2019 to hand out heavy jail sentences to Catalan separatists for their attempt to break the region away from Spain two years earlier.

Sanchez last year pardoned the 11 leaders who had been sentenced to prison terms ranging from nine years to 13 years.

The prime minister's initiative comes ahead of a crucial vote on the 2023 budget in the lower house, where his minority coalition counts on the support of left-wing Catalan separatist party Esquerra Republicana.

Catalan regional President Pere Aragones, from Esquerra, hailed the reform as an important step that will make it harder to "persecute the independence movement unfairly and arbitrarily".

But right-wing Popular Party leader Alberto Nunez Feijoo said the amendment to the law was a clear example of the government seeking to shore up support in parliament.

"I feel I'm right in saying that Sanchez always puts his political interests above Spain's," Feijoo said on Twitter.

Esquerra has said the reform was not part of negotiations with the government to back the budget.

The bill will requalify sedition, a crime that has existed in Spain since 1822, as "aggravated public disorder". The new law will carry a maximum jail sentence of five years for public figures who organize acts of violence or intimidation that "seriously affect public order," according to a draft of the proposal seen by Reuters.

The current law of sedition carries a maximum sentence of 15 years.

A few Catalan separatist leaders fled Spain after the 2017 secession attempt and are currently fighting extradition orders.

Carles Puigdemont, who was Catalan regional chief in 2017 and fled to Belgium, was more sceptical than Aragones about the amendment plan.

"If you are sentenced to jail for organising and calling for a referendum on independence, it doesn't matter whether it is 15 or 5 years in jail - they are criminalising a right," Puigdemont, whose party does not support Sanchez, said on Twitter.

(Reporting by Charlie Devereux and Joan Faus; Editing by Angus MacSwan)