The Sierra Leone police on Friday rejected accusations by Amnesty International that its officers used excessive force to quell riots last year, calling the charges "biased and partial".

The London-based human rights group on Monday called for "impartial and transparent investigations" into the events last August, which resulted in the deaths of six police officers and 27 civilians, according to an official report.

The police released a statement on Wednesday saying that the use of force employed against the protesters was "proportional, reasonable and necessary".

The police also criticised Amnesty for not reporting on the "savagery" which they said led to some police officers being killed.

The authorities imposed a curfew during last year's unrest, which began as peaceful demonstrations by women against the high cost of living in the small and poor West African nation.

To produce its report, Amnesty said it had spoken to witnesses, relatives of the victims, officials, police and civil society groups.

Among the testimonies was that of the father of a 22-year-old woman who "was allegedly shot by security forces" despite the fact "she went to sell vegetable leaves" and wasn't participating in the demonstration.

Sierra Leonean President Julius Maada Bio, who was elected in 2018 and plans to run for a second term, has claimed the riots were aimed at creating an "insurgency" to overthrow the government and has blamed the opposition.