A senior member of the Al Qaeda (search) terror network told U.S. authorities the group had plans to carry out attacks in Japan during the 2002 World Cup (search) soccer tournament, local media reported Saturday.

U.S. authorities advised Japan of the information, which is believed to have come from the militant Islamic group's third-ranking official, Khalid Shaikh Mohammed (search), the daily Sankei newspaper reported, citing anonymous government sources.

The attacks were not carried out because Al Qaeda did not have a network in Japan, which hosted the 2002 event jointly with South Korea, according to the Sankei.

The report said Mohammed was familiar with Japan. During a three-month stay in 1987, he reportedly studied rock-drilling machinery at a plant in central Japan, the newspaper said, citing Japanese security authorities.

Mohammed, a mastermind of the Sept. 11 terrorist attacks, was captured last March in Pakistan and is in U.S. custody.

Kyodo news agency carried a similar report.

Concerns about possible terror threats against Japan or Japanese abroad have intensified in recent months. Many fear that the government's decision to send its military to Iraq to help with reconstruction efforts could draw such attacks.

Last November, an alleged Al Qaeda operative threatened to attack Tokyo if it sent troops to Iraq.

Earlier this week, there were two mortar attacks on a southern Iraqi town where the Japanese troops are based. But Japan's defense chief said they did not appear to be aimed at the soldiers.