The US embassy in Paris advised Washington to start a military-style trade war against any European Union country which opposed genetically modified (GM) crops, newly released WikiLeaks cables show.

In response to moves by France to ban a Monsanto GM corn variety in late 2007, the ambassador, Craig Stapleton, a friend and business partner of former US president George Bush, asked Washington to penalise the EU and particularly countries which did not support the use of GM crops.

"Country team Paris recommends that we calibrate a target retaliation list that causes some pain across the EU since this is a collective responsibility, but that also focuses in part on the worst culprits.

"The list should be measured rather than vicious and must be sustainable over the long term, since we should not expect an early victory. Moving to retaliation will make clear that the current path has real costs to EU interests and could help strengthen European pro-biotech voices," said Stapleton, who with Bush co-owned the St Louis-based Texas Rangers baseball team in the 1990s.

In other newly released cables, US diplomats around the world are found to have pushed GM crops as a strategic government and commercial imperative.

Because many Catholic bishops in developing countries have been vehemently opposed to the controversial crops, the US applied particular pressure to the pope's advisers.

WikiLeaks: US Planned 'Retaliation' Over Opposition to Genetically Modified Crops