Police have seized explosives during a teachers’ protests in Mexico City.
The Interior Ministry announced on Tuesday that 59 explosive devices had been discovered on a bus carrying arriving demonstrators.
The find comes just a few days before the start of the World Cup.
"We support peaceful demonstrations, but the public must not be put at risk by the use of explosive devices during protests," said Arturo Medina, state secretary for human rights at the Ministry of the Interior.
For days, radical members of the CNTE teachers’ union have been demonstrating for the withdrawal of a controversial pension reform.
They are blocking main roads in Mexico City and have set up a tent camp in the historic centre of the capital.
Last week, violent clashes broke out between demonstrators and the police.
The World Cup in Mexico City is due to kick off on Thursday with a concert and the opening match between hosts Mexico and South Africa.
