Brazilian police are investigating after 64 containers with more than 1,400 tonnes of hazardous UK waste were found in three of the country's ports.
The authorities say that among the material which was brought in illegally they discovered batteries, syringes, condoms and nappies.
Since the initial discovery, another 25 containers with hospital waste were found, also apparently from England.
In a statement the British Embassy in Brazil promised "immediate steps".
It said the UK was completely opposed to any kind of illegal trade in waste.
The discovery of the containers has caused widespread anger and comment here with one official saying Brazil was not prepared to be "the world's rubbish bin".
The finds were made in the port of Santos near to Sao Paulo and two other ports in the southern state of Rio Grande do Sul.
The authorities say they fear it may represent an attempt to use South America's largest country as a dumping ground for hazardous waste in the way that has happened in other parts of the world, including Africa.
Among the material found in the containers were batteries, syringes, leftover food, condoms and nappies.
Public resentment over the issue increased when it was revealed that inside one of the containers was a collection of dirty toys with a note in Portuguese saying they should be washed before being given to "poor Brazilian children".
After a further investigation more containers were found in which there is said to be hospital waste including bags full of blood.
Five companies have already been fined in Brazil but lawyers for the importers say they were deceived and believed they were being sent plastic for recycling.
The authorities in Brazil are investigating the possible involvement of two UK companies, and the British Embassy says that, where there has been any breach in the strict international controls on the export of waste, the government will not hesitate to take action.