Brazilian federal prosecutors have charged 11 people with planning to establish a Daesh cell in Brazil and trying to recruit terrorists to send to Syria, according to a court filing seen by Reuters on Thursday.

Police tracked the alleged Daesh terrorists through their social media messages after Spain's Guardia Civil provided telephone numbers found on a Brazilian arrested in Spain for belonging to a terrorist group there.

In one WhatsApp chat group, some of the Brazilian suspects discussed plans to copy last year's London Bridge attack during Carnival in Rio de Janeiro or Salvador to kill as many people as possible, the document said.

Two of the Brazilians are being held in a maximum-security prison and five others, arrested since October, were freed pending trial, said a spokesman for the prosecutors office for the state of Goias in central Brazil that filed the charges.

Police found homemade weapons in the house of one of the suspects, who identified himself in social media messages as a supporter of al Qaeda terrorist group.

It was the second copycat group dismantled by Brazil in two years.

Before the 2016 Rio Olympics, police arrested 10 people suspected of belonging to a poorly organized group supporting Daesh who discussed terrorist acts during the Games.

The Brazilian government described the group as "absolutely amateur" and said its members were in contact via messaging apps but did not know each other personally.