At least two people have been killed in Guinea at the start of open-ended protests against President Alpha Conde's suspected bid to seek a third term in office.

The West African country has been racked by demonstrations since mid-October over concerns that Conde intends to use a planned constitutional reform to seek another five-year term.

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At least 20 civilians and one security officer have been killed since the start of protests, which have drawn hundreds of thousands of people while scores have been arrested.

After months of organising mass protests, the National Front for the Defence of the Constitution (FNDC), an alliance of opposition groups, raised the stakes last week and called for "huge" and "open-ended" demonstrations.

During demonstrations on Monday, scuffles broke out in the Coza suburb of the capital Conakry between young people and the police, according to AFP news agency.

Elhadj Mamadou Sow, a 21-year-old student, was killed in the unrest, according to his uncle, who declined to be named, AFP reported.

A hospital source had earlier told AFP that the 18-year-old was shot in the head, adding that the death prompted protesters to attack a courthouse and the local office of Conde's Guinean People's Assembly (RPG) party.

The security ministry confirmed Sow's death and said an investigation had been launched.

The ministry also confirmed the death of another protester in the northern city of Labe.

Shops and schools were shut across the capital, Conakry on Monday [Screengrab/AFP]

Conde, 81, has neither confirmed nor denied the claim that he put forward a draft constitution last month intending to keep himself in office for a third term.

The current constitution in the former French colony stipulates maximum two five-year presidential terms.

The government on Sunday accused opposition leaders of seeking to plunge Guinea into disorder. The FNDC had called for a peaceful protest.

Guinea's Security Minister Albert Damantang Camara also said on Monday that he has "the manpower, methods and capabilities" to intervene whenever necessary.

Shops and schools were shut across Conakry on Monday, while streets were mostly empty of traffic.

"The FNDC's call for resistance is being widely followed in several cities in Guinea," the opposition group said in a statement.

"This has resulted in a total paralysis of the main roads, the closure of shops and businesses," it added.

The FNDC also confirmed that there had been clashes in Conakry, and in the cities Boffa and N'Zerekore.

Abdourahmane Sanoh, the group's spokesman, told AFP the start of the protest had been "a success".