Rwanda has expressed shock following the death of its former ambassador to Belgium Jacques Bihozagara in jail in Burundi.

Mr Bihozagara died in Mpimba prison nearly four months after being arrested for allegedly spying for Kigali.

Kigali is now demanding answers from the Burundi authorities whom it accuses of detaining him illegally and depriving him of any family visits, amid worsening relations between the two neighbours.

“Mr Jacques Bihozagara is one of many Rwandans in Burundi who died violently or suspiciously in the past months. The Ministry of Foreign Affairs and Cooperation of Rwanda wishes to obtain precise information from the Burundian authorities on the circumstances of his death and clarifications on the reasons for his detention since last December,” said Rwanda's Foreign Affairs Africa director Eugene Ngoga.

News about his demise broke on Wednesday evening on social media, but circumstances that led to his death remained unclear.

Mr Bihozagara, who is said to have been in Bujumbura for private business, was accused of espionage by the Burundian government and arrested on December 4, 2015 by the National Intelligence Service.

“We think that he has been suffering from hypertension, but soon an autopsy is going to be carried out to find the real reason for his death,” said Burundi’s Justice Ministry spokesman Elie Ntungwanayo.

According to a source in Bujumbura central prison (Mpimba), Mr Bihozagara was healthy in the morning , but collapsed suddenly and was rushed to the prison’s health centre where he died.

Relations between the two countries have deteriorated since last May after Kigali accused Bujumbura of harbouring FDLR rebels linked to the 1994 genocide, with the latter accusing Rwanda of meddling in its politics and training Burundian rebels.

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Rwanda has also called on the Burundian authorities to facilitate the family of the deceased in their efforts to repatriate the body home.