The final death toll from an oil pipeline explosion in the Chinese coastal city of Qingdao is 62, local authorities say.

The blast last month ripped roads apart, turning cars over and sending thick black smoke billowing over the city, pictures showed.

The body of the last missing person was found on Monday, the Qingdao city government said in a statement on its verified account on Sina Weibo, a Chinese equivalent of Twitter, taking the number of confirmed dead to 62.

Another 136 people were treated in hospital, it said.

The pipeline, run by state-owned oil giant Sinopec, sprang a leak on November 22 and exploded several hours later as workers sought to repair it.

Seven Sinopec executives have been detained by police but authorities are yet to announce the cause of the incident, according to previous Chinese media reports.

China has a poor record on industrial safety as lax law enforcement and corruption enables business owners to cut corners or offer bribes to evade standards.

Around 28,000 people were killed or went missing in workplace accidents in the first half of this year, state media have reported.