A woman in central Kenya has been jailed for six years for forcing her 13-year-old twin daughters to undergo female genital mutilation (FGM), a charity involved in the case has told the Thomson Reuters Foundation.

Mercy Chege, a director at Plan International, is quoted as saying:

A community member alerted us when they had heard the mother was organising the girls to undergo the cut, so we informed the local authorities.

Unfortunately, we were not able to prevent the circumcision as by the time the police conducted the raid and rescued the girls, they had already been cut."

Florence Muthoni, from Tharaka-Nithi county, was arrested on Wednesday and sentenced by a magistrates court the following day in the town of Chuka, Thomson Reuters Foundation reports.

FGM, which involves removing all or part of a girl or woman's external genitalia - including the clitoris, was outlawed in Kenya in 2011.

But the practice continues in some communities who see it as a rite of passage or as necessary socially if a girl wants to get married.

Ms Chege said the twins were receiving medical treatment.

The police were still investigating the matter as their mother had refused to say who had performed the circumcisions, she added.