Eleven Nigerian military officers were briefly detained in Burkina Faso after their aircraft made an emergency landing in the country, Burkinabè security sources told the BBC.

The Air Force C-130 aircraft entered Burkina Faso's airspace on Monday without authorisation, according to the country's Territorial Administration Minister Emile Zerbo.

In a joint statement, the military governments of Burkina Faso, Mali and Niger said their prompt investigation confirmed the "violation of its airspace and the sovereignty of its member states".

But the Nigerian Air Force (NAF) said a technical problem meant the plane, which was en route to Portugal, had to land in accordance with safety procedures.

The statement added that the crew was "safe and have received cordial treatment from the host authorities". It did not mention whether they had been detained.

The aircraft landed in Bobo-Dioulasso, in the west of Burkina Faso and its second-largest city. The NAF said it was the site of the nearest airfield when the plane had to make an emergency stop.

But the Nigerian account of the incident contradicts the position of the trio of Sahel countries, formally known as Alliance of Sahel States (AES), which said that the aircraft entered Burkinabè airspace without prior authorisation and was forced to land.

"An investigation was immediately opened by the competent Burkinabè services and highlighted the lack of authorisation to fly over Burkinabè territory for this military apparatus," the AES said in a joint statement.

It called the landing an "unfriendly act" and said the countries' respective air forces had been put on maximum alert and authorised to "neutralise any aircraft" found to violate the confederation's airspace.

On board were two crew members and nine passengers, all military officers, according to the AES.

The Burkinabè authorities told BBC that the soldiers were released and given permission to fly back to Nigeria.

In its statement, the NAF said that plans were under way to resume the mission to Portugal as scheduled, assuring the public that the air force remained committed to operational aviation procedures and safety standards.

Political analysts have linked the incident to the deployment of troops from West Africa's regional bloc, Ecowas, to Benin following an attempted coup on Sunday.

Nigeria led the regional mission with the deployment of jets and troops to suppress the mutiny in Benin.

Earlier this year, all the three military-led countries - Burkina Faso, Mali and Niger - withdrew from Ecowas, citing a mix of political and security grievances.

They had rejected Ecowas' demands for them to restore democratic rule.

The three Sahel countries have also distanced themselves from Western countries, notably from former colonial ruler France, while drawing closer to Russia.