Polls have opened in Congo-Brazzaville in a referendum on constitutional changes that would allow President Denis Sassou Nguesso to stand for a third term.

Polling booths were due to open at 7:00 am (0600 universal time) for the ballot on whether to amend the constitution to allow Sassou Nguesso, 71, to stand again for office in the 2016 election.
All traffic except for security forces and those with a special police permit was banned from the roads in Brazzaville and the capital was quiet at the start of voting.
There have been deadly protests in the run-up to the referendum. On Tuesday, authorities said four people were killed in clashes between opposition demonstrators and security forces in Brazzaville and the economic capital Pointe-Noire.
But opposition leader Paul-Marie Mpouele claimed Friday that at least 20 people had died in the unrest and asked opposition supporters "to reject the referendum" but also to "avoid all violent acts".
Sassou Nguesso wants to amend the constitution to change two provisions that disqualify him for running for reelection in 2016.
Under the current charter, the maximum age of presidential candidates is 70 and the maximum number of mandates a person can serve is two.
Sassou Nguesso has already served two consecutive seven-year terms.
He is one of Africa's longest-serving leaders. Having begun his career in the military, he took power in 1979 and has been in office ever since, except for a five-year period.
The president of former colonial power France, Francois Hollande, Wednesday urged Sassou Nguesso to "calm tensions" while emphasising his right to "consult his people".
On October 10, tens of thousands of the president's supporters rallied in Brazzaville in favour of the constitutional changes.
The demonstration was huge in comparison to an anti-government demonstration late last month, when just a few thousand people came out to protest against the proposed constitutional changes.