NICE, France -- Authorities discreetly stepped up security at the Nice international airport Saturday after receiving a letter threatening a toxic gas attack that they dismissed as a probable hoax, a ranking official said.
A long-delayed readiness exercise to counter nuclear, chemical and biological attacks was planned for Sunday, when the letter said the attack would occur, said Francoise Souliman, top aide at the Alpes-Maritime prefecture, or regional government.
"We received a threatening letter. But after analysis by specialized services, it appears rather fanciful," she told The Associated Press.
The letter, written in German and signed by a shadowy group decrying globalization, was received Friday by officials of the Nice-Cote d'Azur airport.
It said Zyklon B gas was hidden in a travel bag and would be released by a long-distance trigger if planes depart or land between 9 a.m. and noon Sunday.
Zyklon B gas was used at the Nazi death camp at Auschwitz during World War II. The letter said the gas was part of a stock seized by Allies when Auschwitz was liberated.
"Threats are regularly received. They all are verified and measures are taken in line with their credibility," Souliman said.
She said an exercise to counter nuclear, gas and biological attacks was set for Sunday. "We're profiting from the occasion to carry out this exercise," she said. Air traffic was to continue normally.
A group calling itself the "EBG," or European Globalization Liberation Front, signed the letter, a copy of which was obtained by the AP.
"We ... aren't demanding any ransom or material assets," the letter said. "We are fighting against the exploitation of people and nature by the forms of globalization."
The letter said the Nice airport was targeted "because in this southern French metropolis on the Mediterranean, commerce with its inhuman characteristics is especially clear."
Nice, a tax haven for the wealthy, is the gateway to the playgrounds of the rich along the Riviera.
In July, letter threats against eight multinational food and cosmetics companies were received claiming their products would be poisoned if they didn't each pay $1.35 million. No evidence of a poison plot was found.
A group calling itself AZF signed the threats. Officials had said the threats appeared unrelated to blackmail attempts earlier in 2004 by a group using the same name that threatened to bomb railway targets unless the government paid them millions of dollars.