A former Rwandan military officer who was sent home from Uganda despite having refugee status was put on trial on Tuesday on charges of trying to overthrow the state.

A former member of the presidential guard protecting Rwandan President Paul Kagame, Joel Mutabazi fled the country in 2011 but was extradited by Ugandan authorities last year. Uganda, which has close relations with Rwanda, insisted it had sent him home "by mistake".

Mutabazi was indicted in mid-November on charges of "terrorism, setting up an armed group, spreading rumours with the intention of inciting the public to rise up against the state, murder, crimes against the state and illegal possession of a firearm".

The court did not give details of Mutabazi's alleged crimes, but the police have accused him of being linked to a string of grenade attacks carried out in Rwanda.

On Tuesday Mutabazi pleaded not guilty, said his trial was illegal and that his life was in danger.

"My home is in Uganda, where I was kidnapped. I'm a refugee who fled Rwanda and I don't understand how a refugee can be tried in a town that he fled," Mutabazi said.

Human Rights Watch and exiled Rwandan groups opposed to strongman Kagame criticised Mutabazi's transfer.

At the end of October, Uganda's Refugees Minister Hillary Onek admitted that Mutabazi had been exfiltrated "in a clandestine manner" from Uganda and cited "an error of judgement" on the part of the Ugandan police.

HRW said that since his arrival in Uganda Mutabazi had already escaped one attempted abduction and an attempt on his life.

One of the two groups that Kigali accuses of being behind the string of grenade attacks over the past several years is the Rwanda National Congress (RNC), an opposition party in exile linked to Patrick Karegeya, the former spy chief found assassinated in South Africa at the beginning of the year.

RNC's leaders are all former members of the ruling Rwandan Patriotic Front, which is led by Kagame and which has dominated the country since its then-rebel army ended the 1994 genocide.

The other group is the Democratic Forces for the Liberation of Rwanda (FDLR), Rwandan Hutu rebels who have been operating in the east of the Democratic Republic of Congo for the best part of the past two decades and which counts in its ranks perpetrators of the genocide.

Kigali considers that the FDLR still constitutes a serious threat to its security.