1213 GMT October 23, 2019
In the case, a man was detained accused of throwing stones at a police car, BBC reported.
When five other men protested at a police station, they too were detained.
Accusations of torture and racist motivation were rejected by the court.
It is the first time so many officers have been convicted in such a case in Portugal, correspondents said.
The six youths, reportedly aged between 23 and 25 at the time, lived in Cova da Moura — a neighborhood predominantly inhabited by immigrants from Cape Verde, a former Portuguese colony in Africa — in the city of Amadora.
Judge Ester Pacheco said there was a ‘serious abuse of authority’ by the officers, who made unjustified arrests and then tried to make it appear the youths had invaded the police station.
The court in Sintra sentenced one officer to 18 months in prison for a repeat offence while the others were given suspended sentences. Their lawyers said they will appeal.
Nine other officers were acquitted.
The victims will receive compensation of €10,000 (£8,800; $11,200), Diário de Notícias newspaper reported.
Pedro Neto, executive director of human rights group Amnesty International in Portugal, said the case "underscores the need for independent and outside control of security forces".
"The state must not fail victims of racism," he added in a statement.