Congolese President Denis Sassou Nguessou arrives to cast his ballot on Sunday in Brazzaville.

Congo votes to amend the constitution Sunday in a referendum allowing President Denis Sassou Nguesso to extend a grip on power that began three decades ago. Sassou Nguesso took power in 1979 and has been in office ever since, except for a five-year period. Here is a list of Africa’s longest-serving leaders:

l 36 years: Teodoro Obiang Nguema Mbasogo, Equatorial Guinea. Came to power in a coup on Aug. 3, 1979. He was officially named president on Oct. 12, 1982.

l 36 years: Jose Eduardo dos Santos, Angola. Leader of the party which won independence from Portugal in 1975, Dos Santos has been in power since Sept. 20, 1979.

l 35 years: Robert Mugabe, Zimbabwe. The only living African leader to have been continuously in power since his country’s independence, Mugabe became prime minister in April 1980 and president in 1987.

l 32 years: Paul Biya, Cameroon. Came to power on Nov. 6, 1982.

l 29 years: Yoweri Museveni, Uganda. Took office in January 1986 after winning the war which ousted the brutal regime of Idi Amin Dada, with help from neighbouring Tanzania.

l 29 years: King Mswati III, Swaziland. Acceded to the throne of the tiny southern African kingdom in April 1986, four years after the death of his father.

l 26 years: Omar Bashir, Sudan. Has ruled since he seized power in a coup in June 1989.

l 25 years: Idriss Deby, Chad. Emerged as the leader of the arid north-central African state in December 1990, after the war which ousted the regime of Hissein Habre.

The longest-serving leaders of post-colonial African countries have been:

l Emperor King Haile Selassie, who was ousted from power in Ethiopia in 1974 after 44 years.

l Muammar Qaddafi of Libya, who ruled his north-African state for almost 42 years after a coup in 1969. Qaddafi was ousted and then killed in 2011 by a rebel movement backed by western warplanes.

l Omar Bongo Ondimba, who ruled the west African state of Gabon for more than 41 years until his death in October 2011. He was then succeeded by his son.

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