BOGOTA -- Colombia and Brazil destroyed 19 illegal gold mining dredges in the Amazon rainforest which were producing about $1.5 million of the precious metal a month and polluting rivers with mercury, Colombia's armed forces said on Wednesday.

Monthly production at the illegal mining operation was 23 kilograms (50.71 lb), Colombian authorities said.

The U.S.-backed bilateral operation targeted the infrastructure of the transnational criminal group Familia del Norte, whose illicit gold mining dumped 114,000 grams of mercury and polluted 68 million liters (18 million gallons) of water every month, according to authorities.

The operation "became a source of financing for weapons and explosives and the acquisition of chemical inputs by the criminal structure known as the Familia del Norte," Colombia's armed forces said in a press release.

Brazil and Colombia are two of the world's most biodiverse nations, with swathes of their landmass covered by the Amazon rainforest, which scientists say is vital to slowing down climate change because of the huge amounts of greenhouse gases it absorbs.

Brazilian President Luiz Inacio Lula da Silva and his Colombian counterpart Gustavo Petro have used their platforms at international events to urge protection of the Amazon, efforts to curb deforestation and debt-for-nature swaps.

In Colombia, 12 three-storey vessels with engine rooms, sediment storage and accommodation were destroyed on the Pure and Purete rivers. Brazilian authorities destroyed seven of these same vessels on their territory.

"We are witnessing a historic bi-national operation against the illegal extraction of mineral deposits, aimed at protecting the lungs of the world," said William Rene Salamanca, director of Colombia's National Police in a statement.

($1 = 3,985.7400 Colombian pesos)