Seven people believed to be responsible for a chemical leak in Quanzhou, Fujian province, have been arrested, the provincial People's Procuratorate said on Tuesday.

Five people — three from Fujian Donggang Petrochemical Industry, the company allegedly responsible for the leak, and two workers from the Tiantong No 1 oil tanker, the vessel transporting the petrochemicals — have been arrested on suspicion of negligence resulting in major consequences, the procuratorate said in a micro blog statement.

The legal representative of the company, surnamed Huang, and its executive deputy general manager, surnamed Chen, have been arrested for allegedly covering up facts to escape punishment, it said.

The incident this month actually involved a leak of 69.1 metric tons of petrochemicals, not the 6.97 tons reported earlier by the company, the local government said on Sunday

The company's attempt to hide the actual volume of the leak and falsify evidence was "terrible", Wang Yongli, mayor of Quanzhou, told a news conference on Sunday.

At 1:13 am on Nov 4, a hose from an oil tanker owned by the company ruptured while offloading toxic petrochemicals at a wharf in Quanzhou's Quangang district.

"After the incident, midlevel and higher employees of the company were told during a meeting to keep the real amount of the leak secret to escape criminal punishment," Wang said.

The aliphatic hydrocarbons that leaked from the hose are oily, pungent chemical compounds typically derived from the oil refining process. Their toxicity is similar to gasoline, and they can cause irritation to skin, eyes and respiratory tracts.

After the chemical leak, 52 people went to hospital complaining of severe headaches, vomiting and sore throats after breathing the air near the site of the spill.