BEIJING - The Ministry of Environmental Protection received 696 public tip-offs about pollution in the first half of the year, more than 75 percent of them about air pollution, it said on Monday.

Others involved water, noise and waste pollution, according to a ministry statement.

All the complaints were lodged through telephone hotline 12369.

The ministry said its investigation confirmed problems in 497 of the reported cases. Companies found responsible received punishments ranging from warnings to suspension, closure and fines.

The industries subject to most complaints were chemicals, non-metallic mineral processing, metal smelting and processing, the ministry said.