By Sergio Goncalves

LISBON (Reuters) -Portugal's centre-right minority government, under pressure from the far right to reduce immigration, said on Monday it would double to 10 years the amount of time most foreigners need to be legally resident in Portugal before applying for citizenship.

Cabinet Minister Antonio Leitao Amaro said other immigration rules, such as those governing the issuance of residence permits for families of legal immigrants, would also be tightened, and there would be a provision stripping naturalised Portuguese who commit serious crimes of their citizenship.

The Iberian country of around 10.5 million people has experienced a significant increase in immigration in recent years and the tightening of requirements to obtain Portuguese citizenship was a central theme in last month's election, in which the far-right Chega became the main opposition party.

The decree is yet to be sent to parliament, but it is expected to be approved with Chega's support.

"We are significantly strengthening the requirements for access to citizenship, naturalisation, in line with the guidelines we were already included in the government's program," Leitao Amaro told reporters.

He said that the 10-year period will apply to most foreigners, but immigrants from Portuguese-speaking countries such as Brazil, Angola or Mozambique will have a 7-year period.

Under existing rules, aside from the five years of residency, foreign citizens must demonstrate sufficient knowledge of Portuguese, no previous sentences of more than three years in prison and must not constitute a threat to national security.

Portugal will now require that they also show familiarity with Portuguese culture, the rights and duties of citizens, declare support for the fundamental principles of a democratic state, and have not served any effective prison sentence.

According to economic data aggregator Pordata, in 2023, the last year for which final data is available, 141,300 foreigners were naturalized, 20% less than in 2022.

The government said in January that more than 400,000 applications were being processed.

The migration and asylum agency AIMA estimates that more than 1.5 million foreign citizens were legally residing in Portugal as of the end of 2024. Brazilians are the largest group, with over 450,000 legal immigrants.

(Reporting by Sergio Goncalves; Editing by Toby Chopra)