Japan has warned its citizens of a possible terrorist attack in Europe. Joining Britain and the United States in alerting travellers to the threat of an impending attack, Japan's Foreign Ministry today said that travellers should be cautious when using public transportation and visiting tourist sites. On Sunday, Britain warned its citizens of a high threat of terrorism in France and Germany. The U.S. State Department has also issued an alert, cautioning Americans of possible terrorist attacks in Europe by al-Qaida and its affiliates. Western intelligence officials last week said, they had uncovered a plot by al-Qaida-linked militants based in Pakistan for terror attacks in major British, French and German cities.