President Alpha Conde, 82, wants to change the constitution to introduce social reforms, but his opponents say his real objective is to modify presidential term limits and run for a third mandate.
After voting began Sunday morning, opposition supporters attacked police deployed outside a polling station in a suburb of the capital, Conakry, AFP, and other witnesses reported. In another school nearby, voting equipment was destroyed.
Guineans have been protesting since October against the possibility of Conde’s representing himself for a third term after the current one expires in December. At least 31 people were killed in the protests.
Last month, Conde postponed the referendum initially scheduled for March 1 after international observers reported some 2.5 million suspect names on the country's electoral register.
The government said it has erased the problematic names, but Guinea's opposition still doubts the vote's credibility.
Former Prime Minister and the head of the leading opposition party Cellou Diallo described the whole election process as a “masquerade.”
Conde became Guinea's first democratically-elected president in 2010. He was re-elected in 2015 for a second and final term under the constitution.
The draft constitution would still limit presidential terms to two but extend their length to six years, potentially enabling Conde to govern for another 12 years.
Guinea's government argues the new constitution would bring necessary social changes in the country, including banning female genital mutilation, under-age marriage and giving spouses equal divorce rights.
The president has not denied that he might use the new constitution to seek another term.
Amid concerns about the credibility of the vote, there were also concerns about the spread of the new coronavirus. Guinea has confirmed two cases so far.