ABUJA, Dec 2, 2025 (BSS/AFP) - Nigeria has granted asylum to Guinea-Bissau opposition leader Fernando Dias da Costa, who ran against ousted president Umaro Sissoco in last week's elections, a foreign affairs official said Monday in Abuja.

The military took control of the coup-prone Portuguese-speaking nation on Wednesday -- a day before the provisional results of national elections were due to be announced.

The powerful opposition African Party for the Independence of Guinea and Cape Verde (PAIGC), said its headquarters had been "illegally invaded by heavily armed militia groups" in Bissau following the coup.

Dias has been granted "protection and security" at the Nigerian embassy in Bissau, according to a leaked letter by the Nigerian Foreign Minister Yusuf Tuggar and cited by Nigerian media.

"The decision of the Federal Government of Nigeria to grant asylum and provide protection to Mr. Fernando Dia Da Costa falls squarely within Nigeria's sovereign responsibility and longstanding commitment to regional peace, stability, and democratic governance," foreign minister's spokesman Alkasim Abdulkadir, said in a text to AFP.

"Acting in the broader interest of de-escalation, Nigeria exercised its lawful discretion to prevent further deterioration of tensions and to promote social cohesion in Guinea-Bissau and the wider West African sub-region.

He said the decision to intervene was "guided solely by the imperatives of peace, human security, and regional stability, in line with ECOWAS principles and Nigeria's historic role as a stabilising force in West Africa".

The opposition leader last week told AFP he believed he had won the November 23 election and alleged Embalo -- who has also claimed victory -- had "organised" the power grab to prevent him taking office.

Dias said he had escaped from his campaign HQ on Wednesday when armed men came to arrest him.

Outgoing Embalo, was arrested on Wednesday but allowed on Thursday to leave for neighbouring Senegal before he moved to the Republic of Congo's capital Brazzaville at the weekend.