A letter bomb exploded Monday in the Brussels office of Hans-Gert Pöttering, a German Christian Democratic representative to the European Parliament who leads the largest political party in parliament, the European People's Party. No one was injured, according to an European Union spokeswoman. The envelope exploded when an employee in the office tried to open it. She dropped the letter immediately and apparently was not hurt. The content of the letter was burned. Security at the European Parliament has subsequently been notched up, and an investigation is under way. Monday’s letter bomb was the fifth attack in the last 10 days with a letter bomb against a representative or institution of the EU. (so)