BRUSSELS (AFP) - Seed from a new genetically modified potato in a field in Sweden.

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Europe slapped a summons on German chemical giant BASF on Monday after a "blunder" allowed seed from a new genetically modified potato to remain in a field in Sweden.

"Obviously there was a blunder which took place," said a spokeswoman for the European Commission, which is responsible for licensing products long labelled 'Frankenfoods' in media.

"The wrong potato was sent to Sweden," the spokeswoman said, triggering the summons to "explain" why "flowers" of Amadea, a GM crop currently being prepared by BASF, but which is not yet authorised, were found in the field.

Brussels is also gathering authorities from Sweden, Germany and the Czech Republic, the three territories where Amflora -- a strain of potato that is authorised for the likes of glue or paper-making, but not human consumption -- is legally grown.

According to Greenpeace, the potato has been "grown illegally in open fields in Sweden for months" by Plant Science Sweden, a subsidiary of BASF.

The environmental campaigners say that while Amadea has been cleared from the field, planted on June 11, Amflora has been allowed to remain, after "a deplorable lapse in bio-security" that a spokeswoman said showed that such companies "can’t be trusted."

Greenpeace said the case echoed one in which "thousands of hectares of unauthorised GM maize had to be destroyed after being grown illegally across Germany this summer."

The commission spokeswoman asked: "Who knows what the effects of growing a largely untested GM crop for months in the open environment will be?"

BASF admitted on its website that it had found "extremely small quantities of Amadea potatoes in Amflora fields" during "regular in-house quality controls."

It said that the "level of comingling is less than 0.01 percent, which translates to 47 Amadea plants among approximately 680,000 Amlora plants," all of which had been "removed."

Amadea was submitted last week for regulatory approval in the EU.