Brig Gen Frank Rusagara, a retired senior Rwandan military officer and diplomat, has been arrested over alleged links to exiled opposition groups.

Rwanda’s defence spokesperson Brig Gen Joseph Nzabamwita confirmed the arrest, but said the reasons would be communicated after ongoing investigations are concluded.

Rusagara, who retired from the army in October last year and then served as Rwanda's Defence Attaché to the United Kingdom, has authored books on Rwanda’s history and transformation over the past 20 years and was part of the Rwanda Patriotic Army (RPA), the armed wing of the Rwanda Patriotic Front (RPF), which stopped the genocide and took power in 1994.

READ: History of the military in Rwanda, by an insider

According to a source, the retired general, who holds a PhD in History, was arrested at the beginning of the week on allegations of "sabotage" and "collaboration" with exiled elements said to be engaged in acts of destabilising the country.

“Brig Gen Rusagara was suspected to be in touch with exiled military officers, including Lt Gen Kayumba Nyamwasa and others who are thought to pose a serious threat to the security of the country and the government,” the source said.

Brig Gen Rusagara’s outspoken nature and the fact that he was becoming critical of the government and some policies are said to have disturbed the government.

A relative, who spoke to The EastAfrican on condition of anonymity, said the general, who is an in-law of the exiled and vocal former Principal Private Secretary to President Paul Kagame, Dr David Himbara, was summoned from London soon after completing his term earlier this year.

According to sources, Brig-Gen Rusagara, who until recently was promoting government programmes such as ‘Ndi Umunyarwanda’ in Europe, had been open about having free conversations with exiled former colleagues with an insistence that ‘political or ideological differences’ cannot come in the way of personal relations.

His arrest brings to the fore tensions that have been simmering in Rwanda’s military after the departure of Chief of Staff Lt Gen Kayumba Nyamwasa and Col Patrick Karegeya, the former head of external intelligence, who are now fugitives.

In July 2012, the military tribunal convicted Lt Col Rugigana Ngabo, a brother of Kayumba Nyamwasa, to 9 years for treason, conspiracy to threaten state security and inciting the public against the government.

Prior to his UK posting, Brig Gen Rusagara served as the Permanent Secretary in the Ministry of Defence as well as the head of Nyakinama Military College.

As a military attaché to the UK, he was also accredited to Switzerland, Sweden, Denmark and other Nordic countries.

It is not the first time Brig Gen has been arrested. In 2007, he was arrested along with Brig Gen Sam Kaka on accusations of obstructing justice. It was alleged that the duo blocked police from arresting businessman Assinapol Rwigara.

They reportedly prevented police from arresting Mr Rwigara who was wanted over an accident that happened at his construction site in which three people died. After a month long trial and detention, the two were acquitted.

Other previous positions held by Brig Gen Rusagara include the Director of the RDF Department of Information, Documentation and Military History, G1 – General Staff Officer in Charge of Personnel and Administration, Director of Finance and President of the Rwanda Military Court.

Brig Gen Rusagara was exiled to Uganda at an early age where he grew up until returning to Rwanda with the RPA. He holds an MA in International Security Studies from the University of Nairobi and a BCom Degree from Makerere University.

Among other books he authored include “Resilience of a Nation: A History of the Military in Rwanda” (2009). He has authored papers including "Gacaca as a Reconciliation and Nation-building Strategy in Post-genocide Rwanda".