Media playback is unsupported on your device Media caption Quan Li lost his wife in the fire in Tianjin

The United Nations' top expert on human rights and hazardous materials has criticised China for a "tragic" lack of transparency on the Tianjin blasts.

UN Special Rapporteur Baskut Tuncak said more timely information could have "perhaps even prevented this disaster".

At least 114 people died and another 700 were injured by massive explosions last week at a warehouse storing hazardous chemicals in Tianjin's port.

The cause it not yet clear, and a massive clean-up is continuing.

Thousands of people saw their homes destroyed or unsafe to return to.

'Deeply disturbing'

Mr Tuncak called on China to ensure transparency in the investigation into the 12 August incident, and to adhere to international standards such as timely and effective dissemination of information in such disasters.

"This chemical disaster serves as yet another tragic example of the need of information about hazardous substances to protect, respect and realise human rights," he said.

"The lack of information when needed - information that could have mitigated or perhaps even prevented this disaster - is truly tragic."

He said there were "deeply disturbing" restrictions on freedom of press and on access to safety information, which could have increased casualties.

China's authorities have come under heavy criticism online, accused of not being clear about the risk of contamination beyond the blast zone, nor about why a warehouse containing dangerous materials was situated close to homes.

The warehouse, owned by Ruihai International Logistics, was less than 1km (0.6 miles) from at least three residential complexes, which flouted Chinese law.

Read more: The questions after the Tianjin blasts

Local officials appeared unprepared for questions and gave vague answers at the first few press conferences. State broadcaster CCTV cut off live broadcasts as journalists continued asking questions.

Discussion on the incident on microblogging network Weibo was also censored, as is usually the case with sensitive incidents.

Media playback is unsupported on your device Media caption Tianjin residents have staged angry protests one week after the blasts calling on the government to buy their damaged homes, as John Sudworth

But with continuing public fury - Tianjin residents have staged protests almost daily - local authorities have in recent days been giving more information on chemical contaminants in waste water and in the air.

Tianjin's mayor Huang Xingguo met the media for the first time on Wednesday, and pledged to relocate all chemical plants to an area 25km from the city centre.

Authorities have promised to compensate residents whose homes were destroyed or damaged by the blast.

State media have reported that Ruihai's owners Yu Xuewei and Dong Shexuan, have also been detained.