ROME, Feb 6 (Reuters) - A leading Italian environmentalist group urged the European Union on Tuesday to ban Monsanto's genetically engineered Roundup Ready (RR) soybeans because of new information about their DNA.

"As a simple precaution, these seeds should be withdrawn from commerce," Ivan Verga, vice-president of Green Environment and Society (VAS), told a news conference.

Monsanto said its product -- which is resistant to the weedkiller Roundup -- was safe and posed no health or environmental threat.

VAS, which has campaigned vigorously against genetically modified foods, presented a Monsanto document at a Rome news conference providing what it called new data about the genetic makeup of RR soybeans.

"Recently, additional characterisation experiments have been completed using more sensitive and precise methods," the Monsanto report said.

"These studies have provided additional details of the inserted DNA," it added, referring to the discovery of two new genetic sequences in RR varieties.

VAS said it had found the Monsanto report, submitted to Britain's Advisory Committee on Novel Food and Processes (ACNFP) last year, on the Internet.

Monsanto, a unit of drug group Pharmacia Corp which listed on the New York Stock Exchange in October, has been at the forefront of controversy over GM crops.

Its Roundup Ready varieties, cultivated by growing numbers of U.S. producers, were authorised for sale in the EU in April 1996. They are popular with many American farmers because their herbicide resistance simplifies crop management.

Verga said his group had written to EU Commission President Romano Prodi urging a ban of RR soybeans as a precaution because of uncertainty over their long-term impact on health and the environment.

His call was supported by Gianni Tamino, a member of Italy's National Bio-Security and Biotechnology Committee, and Roberto Conti, vice-president of a leading consumers' group COOP-Association of National Consumers' Cooperatives.

MONSANTO SAYS RR SOYBEANS SAFE

A Monsanto spokesman said he was surprised that the environmentalists had raised the matter now as the document had been made public several months ago.

"What is new is that we had refined our knowledge about our genetic material," Gabriele Fontana told Reuters, insisting that RR soybeans were safe and posed no environmental risk.

"The review of the safety assessment...confirms the conclusions reached previously that...RR soybeans are as safe and as nutritious as conventional soybean varieties and...do not pose a plant pest risk or otherwise pose a risk to the environment," the Monsanto document said.

MAD COW CRISIS

Tamino said he believed that Monsanto was now riding on the back of the mad cow crisis sweeping Europe.

"It is inevitable that after the EU's ban on meat-based animal feed, Europe will import more soybeans," he said.

The EU banned the use of meat-based animal feed for six months from January 1 in order to reduce and prevent risks from mad cow disease, or bovine spongiform encephalopathy (BSE.) Italy confirmed its first native case of BSE last month.

VAS estimated that GM soybeans accounted for 40 percent of the 10 million tonnes of soybeans a year imported to Italy.

Fontana said he believed GM soybeans probably accounted for a lower percentage but reliable figures were unavailable.

Roundup Ready is the sole GM soybean variety approved for sale in the EU.

A future ban on the import of GM soybeans to the EU could lead European farmers to boost plantings of vegetable proteins, including broad beans and peas, Tamino said.

Italy is the EU's biggest soybean producer by far, growing around one million tonnes a year.