The US embassy in Paris advised Washington to start a military-style trade war against any Euroxpean 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 Dallas/Fort Worth-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.

Cables from the US embassy in the Vatican show that the US believes the pope is broadly supportive of the crops after sustained lobbying of senior Holy See advisers, but regrets that he has not yet stated his support. The US state department special adviser on biotechnology as well as government biotech advisers based in Kenya lobbied Vatican insiders to persuade the pope to declare his backing. "… met with [US monsignor] Fr Michael Osborn of the Pontifical Council Cor Unum, offering a chance to push the Vatican on biotech issues, and an opportunity for post to analyse the current state of play on biotech in the Vatican generally," says one cable in 2008.

"Opportunities exist to press the issue with the Vatican, and in turn to influence a wide segment of the population in Europe and the developing world," says another.

But in a setback, the US embassy found that its closest ally on GM, Cardinal Renato Martino, head of the powerful Pontifical Council for Justice and Peace and the man who mostly represents the pope at the United Nations, had withdrawn his support for the US.

"A Martino deputy told us recently that the cardinal had co-operated with embassy Vatican on biotech over the past two years in part to compensate for his vocal disapproval of the Iraq war and its aftermath – to keep relations with the USG [US government] smooth. According to our source, Martino no longer feels the need to take this approach," says the cable.

In addition, the cables show US diplomats working directly for GM companies such as Monsanto. "In response to recent urgent requests by [Spanish rural affairs ministry] state secretary Josep Puxeu and Monsanto, post requests renewed US government support of Spain's science-based agricultural biotechnology position through high-level US government intervention."

It also emerges that Spain and the US have worked closely together to persuade the EU not to strengthen biotechnology laws. In one cable, the embassy in Madrid writes: "If Spain falls, the rest of Europe will follow."

The cables show that not only did the Spanish government ask the US to keep pressure on Brussels but that the US knew in advance how Spain would vote, even before the Spanish biotech commission had reported.

• This article was amended on 21 January 2011. The original sited the Texas Rangers team in St Louis. This has been corrected.