Dozens of major Chinese firms “severely exceeded” pollution limits in the second quarter of this year, the Environment Ministry said on Wednesday, as the country struggles to combat widespread air, soil and water contamination.

The ministry’s official publication, China Environmental News, said the regions with the most offenders were Inner Mongolia and Liaoning in the industrial northeast, and the country’s top steel producing province, Hebei, which surrounds the capital Beijing.

The ministry said 55 firms had been subject to punitive measures, including tougher supervision arrangements, fines and production restrictions.

Included on the list of firms published by the ministry was the Dalian subsidiary of the state oil giant, PetroChina, which was fined 8.5 million yuan ($1.27 million), as well as a mining firm owned by the Angang Group, a state-owned steelmaker, which was fined 150,000 yuan.

The firms would be compelled to “rectify” their illegal activities and disclose the details to the public. The ministry said 61 of the 95 corporate offenders in the first quarter of the year had already completed rectification efforts.

China has been stepping up efforts to enforce controls on pollution and its traditionally underpowered Environment Ministry has been granted new powers to force firms to toe the line.