A controversial insecticide blamed for the deaths of 13 Bangladeshi children was only banned in the US last year despite being blocked by the EU more than a decade earlier, highlighting the stark differences in safety regulations on either side of the Atlantic.

Researchers at the American Journal of Tropical Medicine found a direct link between the use of endosulfan and the deaths in Bangladesh in 2012.

The children died of acute encephalitis syndrome (AES) after coming into contact with powerful pesticides and fungicides sprayed on lychee orchards in the region.

​Endosulfan, an organochlorine insecticide, is banned due to its health effects in more than 80 countries.

The EU moved to outlaw use of the endosulfan in 2005, while the US waited until 2016 to ban the substance.

The new study, which involved experts at the US Centres for Disease Control and Prevention, looked at the deaths of the children aged between one and 12 years old in northern Bangladesh.

Lead author of the study Saiful Islam, an associate scientist at the International Centre for Diarrheal Disease Research in Bangladesh, said the deaths “were most likely due to an exposure to multiple, highly toxic agrochemicals”.

The report comes as environmentalists warned about the prospect of British negotiators watering down food standards in order to secure a quick trade deal with the US.

A report by a House of Lords committee warned Theresa May not to slash food regulations in order to appease Washington in any future arrangement, saying it could lead to a “race to the bottom for welfare standards”.

In particular, chlorine-washed chicken, hormone-treated beef and genetically modified foods, which are permitted in the US, have sparked concern.

Liam Fox rejects idea that potential reduction in meat safety is important factor in current trade negotiations

Environmentalists warn Britain may be forced to accept lower quality products, including the use of banned flavourings and increased pesticides.

But the International Trade Secretary, Liam Fox, who was in Washington to kick off preliminary trade talks with his US counterparts, played down fears that any agreement would open up British markets to sub-standard agricultural products.

He said: “The British media are obsessed with chlorine-washed chickens, a detail of the very end stage of one sector of a potential free trade agreement.