Companies in Beijing are questioning why the city government has added them to an environmental watch list.

PepsiCo-Beijing, Coca-Cola-Beijing, and Beijing Benz-DaimlerChrysler are among 27 large water and energy-consuming entities included in the list, which was issued on Tuesday by the Beijing Development and Reform Commission, the capital's economic planning agency.

The companies will be subject to monthly inspections of their environmental compliance starting at the end of the month, according to a statement on the commission's website. It did not specify how long the monitoring would last.