The Catholic Institute for International Relations, together with Greenpeace, was condemned for backing "ideological causes ... harmful to the development of Europe" by Dr Peter Raven, a member of the Pontifical Academy of Sciences, at a conference in Rome in September.
The institute said Raven's comments were "potentially defamatory" but it did not want to get into a "ping-pong match" with the American scientist, whose ex-wife is the former head of public policy at Monsanto. But it argues that the views of rank-and-file Catholics need to be heard in a debate which hitherto has been dominated by pro-GM voices.
The conference, called 'Feeding the world: the moral imperatives of biotechnology', was jointly organised by the American embassy to the Holy See (the Vatican) and the Pontifical Academy.
The CIIR says the Vatican is being lobbied by the US Government and biotech companies to back GM. "There was criticism from several places - the Philippines, Africa and Latin America - that the conference panel was too pro-GM and dissenting voices weren't being heard," said Elisabet Lopez, environmental advocacy co-ordinator at the CIIR. "The Vatican has a lot of influence with millions of Catholics. It gives legitimacy to issues."
The CIIR says it is not opposed to GM crops on safety grounds, but is against their promotion as a means of solving world hunger. "We are against the presentation of GM as an integral solution to the problem of world hunger," said Lopez. "It takes attention away from the real issues."
In a statement, the Pontifical Academy of Sciences said GM foods "are essential elements in the development of agricultural systems capable of feeding not only the people that are now hungry, but also meeting the future needs of the growing world population."
CIIR is urging Catholics to "write a personal letter to the Vatican expressing concerns about GM and the way in which biotech corporations are actively seeking the endorsement of the church".