The killings are the latest round of violence in Brazil where workers occupying territory are attacked by armed men linked to plantation owners and illegal logging operations

By Chris Arsenault

RIO DE JANEIRO, April 21 (Thomson Reuters Foundation) - Hooded gunmen killed an estimated 10 people, including children, in a conflict over territory deep in western Brazil's agricultural heartland, government security officials said.

The exact number of dead in Thursday's attack in remote Taquaruçu do Norte in Mato Grosso state on Brazil's border with Bolivia has not yet been confirmed, security forces said in a preliminary statement.

Local security officials did not provide more information about the killings on Friday, a national holiday in Brazil.

Teams of military police mobilized to fly by helicopter to the region to investigate the attacks had been grounded by bad weather, Rogers Jarbas, the state secretary for public security said in a statement late on Thursday.

The killings are the latest round of deadly farm violence in Brazil where landless workers occupying territory are frequently attacked by armed men linked to plantation owners and illegal logging operations, campaigners say.

Violence in the area has been simmering for more than a decade, the Pastoral Land Commission (CPT), a Brazil-based campaign group linked to the Catholic Church said in a statement.

Indigenous and Afro-Brazilian farmers had been living on an estimated 40,000 hectares of disputed territory in Taquaruçu do Norte, before they came under attack, the CPT said.

In 2004, more than 150 families in the municipality were kicked off land where they had been living by armed men thought to be linked to powerful local agricultural interests, the CPT said.

"Historically, these families and communities have lost land to large farmers," the CPT's Thiago Valentim was quoted as saying by the Brazilian news outlet G1.

Last year, 61 people were killed in land conflicts in Brazil, the highest number recorded since 2003, the CPT reported in April.