By Alberto Dabo

BISSAU, Dec 3 (Reuters) - The non-commissioned officer suspected of masterminding an attack on the Guinea-Bissau president's home last month has been arrested in a neighbouring country, an interior ministry spokesman said on Wednesday.

Marine Sergeant Alexandre Tchama Yala, a nephew of opposition leader Koumba Yala whose party rejected its defeat in Nov. 16 parliamentary elections, is suspected of plotting the Nov. 23 attack on President Joao Bernardo "Nino" Vieira's home.

Announcing his arrest, Interior Ministry spokesman Armando Nhaga did not specify in which neighbouring country he was detained, but said he would be extradited to Guinea-Bissau.

In Senegal, which borders Guinea-Bissau to the south, an interior ministry official said a Guinea-Bissau national suspected of being linked to last month's attack was arrested on Monday. The official did not name the detained individual.

On Friday, Guinea-Bissau police said Tchama Yala had fled to Gambia, mainland Africa's smallest country, which is separated from Guinea-Bissau only by a strip of Senegalese territory.

In the Nov. 23 assault on Vieira's residence in the crumbling capital Bissau, hooded military assailants peppered the house with machine guns and rocket-propelled grenades, killing one guard and wounding another.

Authorities in the former Portuguese colony, which has a history of coups and mutinies since its independence in 1974, have detained at least eight soldiers over what they call the latest coup attempt.

Nhaga said the detained included Alfredo Malu, a former state security chief.

The attack failed to unseat veteran leader Vieira, who seized power in a military coup in 1980, was ousted in 1999 after a brief civil war and was voted back to office in 2005.

An associate of Tchama Yala, former Navy chief Rear Admiral Jose America Bubo Na Tchuto, has lived under house arrest in Gambia since he fled there in August after being accused of plotting an earlier coup against Vieira.

Tchama Yala and Bubo are members of Guinea-Bissau's Balante ethnic group, many of whom have opposed Vieira since an alleged Balante military plot against him was bloodily put down in 1986.

Koumba Yala appointed Balantes to top military posts after his election as president in 2000, and the tribe retained key positions even after a bloodless coup ousted him in 2003.

But Koumba Yala's Social Renewal Party (PRS) received a drubbing in the parliamentary elections held on Nov. 16, winning just 28 seats in the 100-seat National Assembly compared with 67 for the former ruling African Party for the Independence of Guinea-Bissau and Cape Verde (PAIGC).

Koumba Yala rejected the results as rigged.

Guinea-Bissau is on West Africa's Atlantic coast which U.N. anti-narcotics officials say well-armed Latin American drug gangs have turned into a "Coke Coast" by using remote islands and airstrips to transship cocaine to Europe for sale. (For full Reuters Africa coverage and to have your say on the top issues, visit: http://africa.reuters.com/) (Additional reporting by Diadie Ba in Dakar; Writing by Pascal Fletcher; Editing by Charles Dick)

AlertNet news is provided by