Environmental Protection Agency (EPA) administrator Stephen Johnson has rejected a request from California and two other states to waive requirements that petrol contain an additive to reduce air pollution, the Los Angeles Times said.

Johnson reportedly said the states had not shown that using an oxygenate would interfere with their ability to meet federal air standards - as a result, the waiver request was denied.

The LA Times said the decision was criticised by California senator Dianne Feinstein, state governor Arnold Schwarzenegger and officials from New York and Connecticut - the other states that had requested waivers - but was praised by corn growers and manufacturers of ethanol, an oxygenate made from corn.

"With this decision, the EPA continues to acknowledge the proven benefits ethanol has on air quality," Leon Corzine, the president of the National Corn Growers Association, reportedly said in a statement.

The LA Times noted that substances most commonly used as oxygenates are ethanol and MTBE, or methyl tertiary butyl ether but California banned MTBE in March 1999 because of concerns over groundwater contamination from leaks in storage tanks.

In April 1999, then-governor Gray Davis requested a waiver from the oxygenate mandate and, in 2001, the Environmental Protection Agency denied California's application, saying the state did not demonstrate what the effect on the ozone level would be if the waiver were granted, the report added.

As a result, the LA Times noted, California is compelled to blend ethanol with petrol, raising the cost and, critics say, increasing air pollution in the summer - the state has the most stringent gasoline standards in the nation and has reduced emissions without requiring such additives.

"The California Air Resources Board researched this issue at length and found that ethanol-blended gasoline does not help California meet the goals of the Clean Air Act as it relates to ozone formation," Feinstein reportedly said in a statement. "In fact, ethanol actually increases the emission of pollutants that cause ozone in the summer months."