TIANJIN, China (AFP/REUTERS) - The death toll from two massive explosions in the Chinese port of Tianjin has risen to 112, an official said on Sunday.

The official Xinhua news agency also said on Sunday that 95 people are missing, suggesting the toll could rise significantly. Eighty-five of the missing from last Wednesday's disaster are firefighters.

"By 9am on Aug 16, the total number of deaths was 112," Mr Gong Jiansheng, the deputy chief of the city's propaganda department, said at a news conference.

"We have already identified 24 bodies, and there are 88 to be identified."

At least 21 firefighters are among the dead, according to state media.

More than 700 people have also been hospitalised as a result of Wednesday's blasts - which triggered a huge fireball - as well as a fire that emergency workers have struggled to put out since then and fresh explosions on Saturday.

The authorities on Saturday moved to relocate anyone within 3km of the blast site in the northern city over fears of toxic contamination, but have insisted that the disaster did not release dangerous levels of chemicals into the environment.

China evacuated residents who had taken refuge in a school near the site of the blasts on Saturday after a change in wind direction prompted fears that toxic chemical particles could be blown inland.

It was not clear from media reports how many people were evacuated, but the order came as a fire broke out again at the blast site, a warehouse specially designed to store dangerous chemicals, according to Xinhua.

It was also not immediately clear if that threat of toxic pollution persisted on Sunday.

Some 6,300 people have been displaced by the blasts with around 722 injured, Xinhua said earlier.

Shockwaves from the explosions were felt by residents in apartment blocks kilometres away in the city of 15 million people.

Officials have struggled to identify the substances present at the scene, sparking fears and scepticism among the residents of Tianjin.

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