Serbian police have gone on strike in a dispute involving unpaid travel and per diem expenses, the president of the Police Union of Serbia said. Veljko Mijailovic said all 27 police departments in Serbia -- about 13,000 employees -- went on strike Monday and will continue the work stoppage until workers are paid money due them. Thje Serbian news agency Tanjug reported that seven police trade unions reached an agreement with Interior Minister Ivica Dacic to end the strike but no details were given.