Clouds of dark smoke billow out over the explosion sites, hours after the two blasts occurred.

Vast areas of Tianjin's port - the 10th largest in the world - were devastated after two huge explosions tore through an industrial area where toxic chemicals and gas were stored late yesterday.

Crumpled shipping containers were thrown around like match sticks, hundreds of new cars were torched and port buildings left as burnt-out shells, Reuters witnesses said.

The blasts in the northeast Chinese port city have killed at least 50 people, including at least a dozen fire fighters, officials and state media said.

At least 701  people were injured, more than 71 of them seriously, the Tianjin government said.

China's President Xi Jinping said in a statement carried by official media that those responsible should be "severely handled".