Three soldiers were killed by a bomb near their patrol in Iskandiriyah, 50 kilometres (30 miles) from Baghdad, a police officer in the Babil provincial capital of Hilla said. Among the dead was an army captain.
Another roadside bomb in a Iskandiriyah market also killed two people, including a woman, the officer said, speaking on condition of anonymity.
Iskandiriyah lies within a confessionally mixed region known as the "Triangle of Death" because of the frequency of insurgent attacks during the worst of Iraq's insurgency after the 2003 US-led invasion.
While violence is down across Iraq since its 2006-2007 peak, attacks remain common. Government figures show that 259 people -- 159 civilians, 55 policemen and 45 soldiers -- died in violence in January.