* Attack aimed to return to power deposed PM, says government
* Assailants "came from outside" (Adds comments from Brazil and Cape Verde, paragraphs 11-14)
By Alberto Dabo
BISSAU, Oct 22 (Reuters) - Guinea-Bissau's interim government accused Portugal and other Portuguese-speaking countries of being behind an assault on an air force base, saying it was part of a strategy to return to power the West African nation's exiled former prime minister.
The military of the tiny coup-prone former Portuguese colony repelled the attack near the capital Bissau early on Sunday during a two-hour gun battle that killed six people.
"The attack ... is part of the strategy to bring (ex-prime minister) Carlos Gomes Junior back to Guinea-Bissau, even at the cost of human lives," government spokesman Fernando Vaz said in a statement read on state radio on Sunday night.
"The tone of the speeches given by Portugal, the Community of Portuguese-speaking Countries (CPLP) and Carlos Gomes Junior was the precursor to the attack," he said.
Guinea-Bissau, a transit hub for Latin American cocaine smuggled to Europe, is in the throes of a ragged recovery after the army overthrew the government in April just weeks before a second round presidential vote Gomes Junior was favoured to win.
The junta said Gomes Junior had a secret pact with Angola, which had soldiers deployed in Bissau at the time, to eliminate the military's leadership.
The West African regional bloc ECOWAS brokered a deal that allowed a handover of power to a civilian interim government charged with setting up new elections.
But interim president Manuel Sherifo Nhamadjo lacks the full support of the United Nations, the European Union and the CPLP, however, who say his government remains under army influence.
Portugal's foreign ministry said on Monday it would not react to the accusations it was involved in Sunday's events. It said earlier that it viewed the situation in the country "with concern after another case of military movements.
"There is no military solution to problems faced by Guinea Bissau. Only via a political process will it be possible to overcome the current crisis situation in this friendly country," the statement read.
Brazil Foreign Minister Antonio Patriota said stabilising Guinea-Bissau will be a test for its partners.
"This will be a test for the subregional and multilateral system: if it cannot establish a strategy of stabilisation for Guinea-Bissau, it is hard to imagine how it will handle bigger challenges when they arise," Patriota told reporters after meeting with visiting Cape Verde Foreign Minister Jorge Borges.
Borges said West African nations were concerned that drug trafficking and terrorism were undermining the stability of Guinea-Bissau and Mali. Coups have become cyclical in Guinea-Bissau, he said.
"The Guinea-Bissau people are hostage to a group of politicians and military officers who do not dignify or contribute in any way to the normal and desirable development of the nation," Borges said.
The governments of other members of the CPLP grouping of Portuguese-speaking countries Angola, Mozambique, Sao Tome and Principe and East Timor, had no immediate comment.
The country's interim prime minister said on Monday that four of the six gunmen killed were from the Djolla ethnic group, common in neighbouring Senegal's southern Casamance region. An unknown number of attackers were also taken prisoner and others remain at large.
"This attack did not come from inside the country and not from the security and defence forces either. The attack ... came from outside," transitional Prime Minister Rui Duarte de Barros said during a meeting with diplomats.
Duarte de Barros said the attempted counter-coup was led by Captain Pansao Ntchama, a bodyguard to the former head of the army under Gomes Junior.
He said Ntchama had used a vehicle belonging to Thomas Barboza, a former member of Gomes Junior's government, to carry out the attack. He did not elaborate on how he knew this. The vehicle was later recovered loaded with ammunition.
The authorities also arrested the leader of a political bloc opposed to the junta, accusing him of having been involved in the attack.
Gomes Junior, who is currently living in exile in Portugal, was not immediately reachable for comment.
Decades of turmoil and regular military coups since it won independence in 1974 have ballooned the size of the army and made Guinea-Bissau's maze of mangrove-lined islands a smuggling route for Latin American drugs cartels.
The elections earlier this year were meant to put the country on the road to stability and to improve its ability to clamp down on drugs trafficking. (Reporting by Alberto Dabo; Additional reporting by Anthony Boadle in Brasilia; Writing by Joe Bavier; Editing by Jon Hemming)