President Aziz is pushing to abolish the country's Senate and several other state bodies and to make a small alteration to the national flag
Mauritania awaits results of contentious referendum on Senate
Counting began on Saturday in Mauritania after a referendum on constitutional changes sought by president Mohamed Ould Abdel Aziz, who derided the efforts of a boycott movement that has galvanised mass protests during the campaign.
Mr Aziz is pushing to abolish the country's Senate and several other state bodies and to make a small alteration to the national flag, measures that have galvanised boycotters hoping to sap the vote's credibility by forcing a low turnout.
Polling stations closed at 7pm local time after peaceful voting, with no repeat of the violent clashes seen in the final week of campaigning.
After voting in the morning, Mr Aziz said the changes would bring Mauritania "peace, security, stability and development", and dismissed the boycott movement as existing "only on paper and social media".
The boycott movement draws broad political support from figures as diverse as religious conservatives and anti-slavery activists.
They have held several protests attracting thousands of supporters, but have also been prevented from demonstrating by the security forces, who on Thursday shut down several planned rallies close to the capital with tear gas and beat protesters back with batons.
Bedenna Ould Sidi, the head of operations for the country's electoral commission, said the referendum had been a success but turnout was not available.
While Mr Aziz and his supporters are seeking a "Yes" vote, one moderate opposition party is seeking a "No", while the rest have joined civil society groups to call for a total boycott for amendments they consider unconstitutional.
The Forum for Unity and Democracy (FNDU), a coalition of parties spearheading the boycott, thanked the Mauritanian people for their "positive response" on Saturday night and said they believed turnout had not broken 15 per cent.
They repeated earlier claims that Mr Aziz's supporters would arrange for a "vast fraud" to win the vote and promised to reveal tactics aimed at pushing through what they termed an "anticonstitutional farce".
The UN Human Rights Office said Thursday that "protest leaders were reportedly beaten up and a number of them were arrested" during campaign rallies in the last few weeks, urging the government to ensure fair and credible elections.
The opposition also fears that despite Mr Aziz's claims to the contrary, he is laying the groundwork for a third term in power, as his own prime minister said back in July he supported the idea.
Mr Aziz himself fuelled speculation on Saturday by saying that "in two years, or even 10 years other amendments could arise to adapt our constitution to reality," without elaborating.
He also said journalists questioning why EU observers were not present had a "colonial mentality", describing the EU as "not a barometer for the truth".
Mr Sidi, the polling chief, said foreign observers were present but would not be drawn on where they had come from.
Aziz vs Senate
The proposal to modify the constitution, in force since 1991, was rejected by the Senate in March, leading Mr Aziz to call the referendum to push through the changes.
The most contentious measure remains the abolition of the Senate and its replacement with elected regional councils, and senators have held a sit-in this week and demanded apologies from Mr Aziz for accusing them of corruption.
Unrepentant, Mr Aziz said at a final rally on Thursday the Senate "costs a lot, has no use and does nothing", and vowed to launch legal action against several senators.
The president came to power in a coup in 2008 and was elected in 2009 and again in 2014 for a second five-year term.
Under the proposed change to the flag, red bands would be added to the current green flag with yellow Islamic crescent and star, to honour those who fought for freedom from colonial master France.