Brazzaville (AFP) - Congo's interior minister on Friday opened the campaigning period ahead of an October 25 referendum on whether veteran leader Denis Sassou Nguesso should be allowed to run for a controversial third term.
The constitution currently bars the 72-year-old, who has already had three decades in power, from seeking another presidential term as there is an age limit of 70 as well as a ceiling of two mandates.
Sassou Nguesso is among several African leaders who have sparked controversy by seeking to extend their stranglehold on power and the move prompted a massive protest in the country's capital Brazzaville when announced last month.
Similar recent moves by his peers have resulted in violence, notably in nearby Burundi where President Pierre Nkurunziza's controversial and globally condemned third term sparked an abortive coup and a sweeping crackdown.
And late last year, the iron-fisted ruler of Burkina Faso, Blaise Compaore, was toppled by popular street protests after trying to prolong his 27-year-rule and a recent coup attempt by one of his closest aides only lasted a week.
The Congolese government said late Monday that the October 25 referendum would be on scrapping both the two-term limit for presidential candidates and the age cap.
"In conformity with the law, the vote will be preceded by an electoral campaign that was declared open from October 9 to 23 at midnight," Interior Minister Raymond Mboulou said in a statement that was carried by the oil-rich state's radio and television channels.
The campaign "must be carried out in a climate of social peace, a climate of tolerance, of acceptance of different opinions, a climate that excludes provocations... and which fundamentally preserves the public order," Mboulou added.
In the south of the capital Brazzaville on Friday, police used tear gas to disperse a protest of several dozen activists who oppose the bid to change the constitution, residents told AFP.
Officials said six people who were detained during the protest were being held for questioning.
Sassou supporters are meanwhile planning to hold a rally on Saturday afternoon in the same neighbourhood where the opposition staged a huge demonstration on September 27 to denounce his bid to stay in power.
The 72-year-old president has previously convened a "national dialogue", which came out "by a large majority" in favour of amending the constitution to remove the term and age limits.
The changes would effectively pave the way for him to stand for a third term in 2016 -- in what the opposition have branded a "constitutional coup".
Sassou Nguesso was president from 1979 until 1992. He then served as opposition leader and returned to power at the end of a brief civil war in 1997 in which his rebel forces ousted president Pascal Lissouba.
He was elected president in 2002, then again in 2009, prompting cries of fraud from his foes.