The death toll from devastating explosions in China's port of Tianjin has risen to 112 and 95 people, most of them firefighters, are missing, state media said on Sunday, suggesting the toll will rise significantly.

More than 720 people remained in hospital four days after Wednesday's disaster, which sent enormous yellow and orange fireballs into the sky, rained burning debris on to a vast industrial zone, crumpled cars and shipping containers, burned out buildings and shattered windows of nearby apartments.

President Xi Jinping on Saturday urged authorities to improve safety and learn lessons paid for with blood.