China on Wednesday announced new measures to control dust ahead of this year's Olympics in Beijing with a top official promising air clean enough to allow athletes to set new records in the city.

A government circular orders construction sites to stop earthwork on windy days from March 20 and bans all construction in Beijing from July 21 ahead of the August 8-24 Games, state media said.

Foreign Minister Yang Jiechi said athletes would have chances to break Olympic records in Beijing.

"I believe the air quality in Beijing will only become better and better," Yang said on the sidelines of the ongoing National People's Congress, China's nominal parliament.

Yang was responding to a question about an announcement by Haile Gebrselassie, an Ethiopian marathon world record holder who suffers from asthma, that he is unlikely to enter the Beijing Olympic marathon because of health concerns.

On Tuesday, another official said plans were in place for Beijing's neighbouring provinces to suspend or reduce production at coal-burning factories and power plants before and during the Games.

"So far, the mission of cutting down pollution and adjusting industrial structure has been largely done and will be fully completed by the end of June," said Zhang Lijun, Vice Minister of the State Environmental Protection Administration.

International Olympic Committee (IOC) officials have also expressed confidence that Beijing could improve its air quality sufficiently to allow athletes to compete normally.

The UN Environmental Programme said in October that the relocation of major polluting industries, a switch away from coal burning and the scrapping of highly polluting vehicles in Beijing had spurred a fall in concentrations of several key air pollutants, including sulphur dioxide and carbon monoxide.

But the agency said Beijing's level of small suspended particles, known as PM10, often greatly exceeded World Health Organisation guidelines.

Dust storms and mountains blocking the circulation of air in Beijing worsen the problem, the UN agency said.

The Chinese government said Olympic traffic control measures tested in August had removed an average of about 1.3 million of the city's 3 million vehicles per day from Beijing's roads and cut emissions of major air pollutants by up to 20 percent.