The French government said Monday that it was the victim of a "spectacular" cyber attack from hackers using Internet addresses in China who targeted documents on international economic affairs.

The hackers were hunting for documents relating to the Group of 20 (G-20) developed and developing nations, which this year is led by France, said Budget Minister Francois Baroin, adding that a probe was underway into the attacks, AFP reported.

"We have leads," Baroin told Europe 1 radio, saying that what he called a "spectacular" attack was "probably the first time" that the French government's computer system was hit by an attack on this scale.

Paris-Match magazine said the finance ministry had come under sustained attack since December.

Patrick Pailloux, director general of the French National Agency for Information Technology Security, told the magazine that the hackers were after "documents related to the French presidency of the G-20 and to international economic affairs."

"The actors were determined professionals and organized. It is the first attack of this size and scale against the French state," he added.

A senior official, who declined to be named, told the magazine that pirated documents were moved to Chinese Internet addresses.

"We know that a certain amount of information was redirected to Chinese sites, but we can't tell much from this," said the official.

The Chinese government has consistently denied supporting hacking, amid a string of attacks on multinational corporations including banks and oil firms, as well as an attack on Canadian government computers, were traced back to Chinese servers.

On Sunday, a South Korean opposition lawmaker said that Chinese hackers gained access last June to secret South Korean military files on a planned spy plane purchase from the U.S., Chosun Ilbo newspaper reported.

"A government official reported the incident to me ... the government has not raised the issue with China yet and is still debating how to handle it," said a spokeswoman for Shin Hak-yon, who sits on the parliamentary defense committee.

Seoul earmarked $40 million for the spy plane purchase following North Korea's attack on a South Korean warship last March that left 46 sailors dead.