Angola's powerful veteran president Jose Eduardo dos Santos, Africa's second-longest serving leader after 36 years at the helm, on Friday said he would leave politics in 2018, after his current mandate ends.

"I have taken the decision to quit political life in 2018," he told the ruling Popular Movement for the Liberation of Angola (MPLA) party politburo in the capital Luanda.

The 73-year-old has been in office just one month less than Africa's record-holder, Equatorial Guinea's Teodoro Obiang Nguema.

The Angolan leader's tenure ends in late 2017, but he did not indicate why he would leave the year after. Analysts suggest he may run for re-election, leaving only once he feels secure about the future.

In power for almost four decades as president, Dos Santos has consolidated political power in his time in office while his family has amassed a vast business empire.

He added another five years to his reign by taking a large victory in a disputed election in 2012, but since has faced growing discontent from the nation's youth.

Critics accuse President dos Santos of overseeing corruption, misrule, arbitrary arrests and intimidation.

Business empire

Paula Roque, expert researcher on Angola with Oxford University, believes that the unexpected announcement offers "no assurance that one of Africa longest heads of state will finally step down."

"What he is saying by announcing that he will step down in 2018 is that he will run in the next poll and then decide if the country is stable enough to step down," said Roque.

Dos Santos came to power in 1979, following the unexpected death from cancer of Angola's liberation president Agostinho Neto.

As head of the military, police and cabinet, the leader has an iron grip on all aspects of power in Africa's second biggest oil producer.

He names the senior judges and has MPLA allies in all public agencies, including the supposedly independent electoral commission.

Roque believes that President dos Santos could be grooming one of his children to succeed him.

Few publicly criticise him. Independent journalists who express their opinions risk criminal charges.

A group of youth activists are currently standing trial on charges of "rebellion" and attempting to carry out a "coup".

Although he shuns the spotlight, the elderly leader's family has built up a vast business empire, with his daughter Isabel dos Santos ranked Africa's richest woman.

Despite the country's oil and diamond riches, the majority of the population live in abject poverty, with an enormous gap between the rich and poor.

Angola in 2002 emerged from a 27-year civil war which left thousands of people dead, but the country has held several elections since independence from Portugal in 1975.