A government probe has found that pollution is affecting people

About 40 workers at three Pluspetrol facilities in the Amazon jungle were caught up in the protest. The company said the staff were not taken hostage.

The protestors claim that their health has been affected by pollutants, such as lead and cadmium, from the oil work.

Pluspetrol said old oil wells, and not its operations, were causing problems.

The Argentinean company said that it was working with authorities and local communities to ensure the cleanliness of the river and help develop projects including fish farms.

'In the water'

A survey carried out by Peru's Ministry of Health earlier this year found that cadmium levels in the blood of more than 98% of the local Achuar people exceeded safe levels.

And more than 66% of children had levels of lead in their blood which exceeded the maximum permissible.

The protests were organised by the Native Federation of the Corrientes River (FECONACO).

The group claims that for every barrel of oil extracted there are nine barrels of contaminated water produced as a by-product.

The Ministry of Health report found that the water contained high concentrations of hydrocarbons and heavy metals, such as lead, cadmium, mercury and arsenic, and the Achuar people say it is destroying the fragile eco-system in which they live.