He added that the power companies needed to clean up their act in order for Hong Kong to comply with an agreement on emission standards with the Guangdong government to cut air pollution levels by 2010.

"I'm determined to ensure that this standard will be complied with by the power companies and I will consider it in the context of the renewal of the scheme of control which will expire in 2008," Tsang said.

The scheme of control is a contractual agreement between the Hong Kong government and the two local power companies -- CLP Holdings and Hong Kong Electric Holdings Ltd -- governing pricing and profitability.

With the agreement due to expire in 2008 -- green groups have pressed the Hong Kong government to force the power companies to comply with more stringent environmental standards -- as a pre-condition for renewal.

In recent years, Hong Kong's worsening air pollution has become a growing cause of concern, affecting public health and even scaring foreign businesses away from the territory.

Whilst coal-fired power companies are largely responsible for air pollution in the city, thousands of Hong Kong owned factories in the Pearl River Delta have also been blamed for the regular bad-air days plaguing the city.