British retailers have again threatened to stop purchasing products from Brazil due to proposed land reforms.

Supermarkets including Tesco, Sainsbury’s and Aldi have penned an open letter to politicians in the Brazilian National Congress urging them to dismiss the proposal, which according to conservationists would open up the Amazon to accelerated deforestation, Sky News reports.

The plan was first proposed last year but cancelled due to a global backlash.

According to opponents, should the law be passed, more forests could be burned and cleared for agriculture, devastating work to tackle climate change.

Under President Jair Bolsanaro’s leadership, the level of deforestation in the Amazon is the highest since 2008, BBC reports.

The companies who wrote the open letter say they "consider the Amazon as a vital part of the earth system that's essential to the security of our planet, as well as being a critical part of a prosperous future for Brazilians and all of society."

The letter went on to add: "Over the past year, we have seen a series of circumstances result in extremely high levels of forest fires and deforestation in Brazil.

"At the same time, we have noted that the targets to reduce these levels, as well as the enforcement budgets available to deliver them, are increasingly inadequate.

"It is therefore extremely concerning to see that the same measure we responded to last year is being put forward again as the legislative proposal... with potentially even greater threats to the Amazon than before."

The letter cautioned: "If this or other measures that undermine these existing protections become law, we will have no choice but to reconsider our support and use of the Brazilian agricultural commodity supply chain."

Talking about the imminent vote, Mike Barrett, executive director of science and conservation at WWF-UK stated: "We cannot fight the climate crisis without the Amazon, yet its future hangs in the balance as deforestation pushes it closer to the point of collapse.

"If passed, this vote in the Brazilian Congress will fuel further destruction and place greater risk on the lives of the people and wildlife who call it home.

"As global efforts to protect the Amazon threaten to be undermined, it's encouraging to see major businesses sounding the alarm."