Authorities in Burkina Faso have charged a general who led a failed coup in September with complicity in the 1987 assassination of President Thomas Sankara, senior security sources told Reuters.

Sankara's murder is one of the most high-profile killings in Africa's post-independence history and the charge against General Gilbert Diendere appears to represent a breakthrough in a case that has haunted the West African country for decades.

It follows a pledge by the transitional government to investigate the murder and a decision in May to exhume the remains of a body believed to be Sankara's, which was buried at a cemetery on the outskirts of the capital Ouagadougou.

"General Gilbert Diendere is formally charged in the Thomas Sankara case," said a senior security source with direct knowledge of the case. Diendere was charged last month with complicity in assassination and attack, the source said.

Diendere's lawyer, Mathieu Some, told Reuters on Sunday his client had been charged over Sankara's death and he would prepare his legal defence. The charges are yet to be made public.

Ten others, less senior than Diendere, have already been charged. The senior security official said most were soldiers in the elite presidential guard of former President Blaise Compaore, who was ousted in October 2014.

Diendere was Compaore's intelligence chief and right-hand man. In September, he led the presidential guard in a short-lived coup in which soldiers took transitional President Michel Kafando and the prime minister hostage.

The coup failed and in its aftermath, the presidential guard was disbanded and Diendere sought refuge at the Vatican embassy. He was then arrested and charged with murder and threatening state security. He is still in detention.

"Africa's Che Guevara"

Sankara took power in a coup in 1983 and pursued a philosophy of Marxism and pan-Africanism that led him to be called "Africa's Che Guevara".

Many African intellectuals view him as a visionary on a par with Congo's first prime minister Patrice Lumumba, who was murdered in 1961, or South African anti-apartheid leader Steve Biko, who was killed in 1977.

He nationalized land and mineral wealth, moved to improve health and education, pressed for debt reduction, promoted women into leadership and changed the country's name from Upper Volta. The changes made an impact on Burkina Faso, a landlocked country that produces gold and cotton but remains impoverished.

Sankara was known for his trademark red beret and rejection of the lavish lifestyle typical of African leaders. In October 1987, he was murdered in a coup that brought Compaore to power.

Compaore reversed many of Sankara's policies and established a reputation as one of the region's most powerful men but mystery surrounding the killing dogged him, not least because attempts to mount a judicial investigation during his tenure stalled.

Compaore was toppled by protesters who opposed his bid to change the constitution so that he could extend his rule.

The charges against Diendere come at a critical moment for Burkina Faso as it makes a democratic transition that is seen as an example for other African states.

Voters elected former Prime Minister Roch Marc Kabore as president a week ago and when sworn in he will be the country's first new leader in decades.

Kabore was an ally of Compaore who went into opposition in early 2014. The election was key for a nation ruled by leaders who came to power in coups for most of its history since independence from France in 1960.