MADRID (Reuters) -Spain's acting Prime Minister Pedro Sanchez looked assured of another term in office on Friday after securing the backing of two more regional parties, but it comes amid widespread anger over his pledge of amnesty for Catalan separatists.

The confirmed support of the National Basque Party (PNV) and the Canaries' Coalition, along with that of Catalan separatist party Junts confirmed on Thursday, would take Sanchez over the line with an absolute majority in the 350-member lower house in a vote due to take place in the coming days.

"We have managed to secure a majority that will make possible the investiture of Pedro Sanchez," acting minister for parliamentary relations Felix Bolanos said in an interview with SER radio station.

The more complicated deal was the one secured on Thursday with Junts, which includes passing a law granting amnesty to those convicted over Catalonia's attempt to secede from Spain in 2017.

"We have very far apart and different positions but this deal means we are doing our best to understand each other. Spain and Catalonia deserve that," Bolanos said.

After an inconclusive election held on July 23, Sanchez's Socialist Party spent weeks negotiating with smaller parties including far-left platform Sumar and Catalan, Galician and Basque nationalist parties, most of which had supported Sanchez early in 2020 for his previous term.

With Junts and PNV and the national and regional left wing parties, Sanchez would win an absolute majority of 178 out of 350 lawmakers.

Later on Friday, the Socialist Party added one vote more to its wide coalition after Canary Islands' regionalist party Coalicion Canaria also agreed to back Sanchez.

Bolanos said the Catalan amnesty law would help ease tension in Catalonia as it would free school directors, firefighters and other civil servants who helped organise an illegal referendum on the region's independence in 2017 from legal proceedings.

The most divisive aspect of the proposed amnesty though is it would allow Catalan separatist leaders such as Junts head Carles Puigdemont, who fled the country in the wake of the referendum and a short-lived unilateral independence declaration, to run for office again.

Sanchez's conservative opponents have accused him of putting the rule of law in Spain on the line for his own political gain. Spanish judges have also said an amnesty would be a violation of the principles of constitutional checks and balances.

As a deal between Junts and the Socialists edged nearer in the past week, the mood in the country became increasingly febrile, with protesters clashing with police outside the Socialists' headquarters in Madrid each evening.

Police fired rubber bullets, 24 people were arrested and seven police officers were lightly wounded on Thursday evening, authorities said, as officers tried to break up the demonstration.

(Reporting by Belen Carreno, Emma Pinedo and Inti Landauro, editing by Aislinn Laing, Toby Chopra and Nick Macfie)