BAGHDAD, June 9 (Reuters) - A suicide truck bomber killed 12 Iraqi soldiers and wounded 30 in an attack on an army checkpoint south of Baghdad on Saturday, police said. There was some confusion over whether the huge explosion happened in Jurf al-Sakhar near the predominantly Shi'ite city of Hilla, 100 km (60 miles) south of the capital, or nearby al-Iskandiriya. Soldiers were digging through the rubble and the death toll was expected to rise, police said.