Chinese state media say forestry officials in far western China have resorted to scattering abortion pills near gerbil burrows in a bid to halt a rodent plague threatening the desert region's ecosystem.

Xinhua News Agency says the pellets have "little effect on other animals" but can prevent pregnancy in gerbils and also induce abortions.

In 2003, officials installed hundreds of perches for owls and eagles hoping the birds would cut back the rodent population, but gerbils have continued to be a problem.

Xinhua says gerbils use too much of the area's limited grass to make their burrows and damage plant roots with their digging.

Deserts are a major concern for China. Deserts currently cover about one-third of the country and officials fear global warming will accelerate their expansion.

The report did not say what was in the "tailor-made" contraceptive pellets, which have been used in the Gurbantunggut desert since May of last year.

"It's a good way to tackle the desert rat plague," local forestry official Du Yuefei was quoted as saying.

Du, chief of the epidemic prevention division of the Changji city forestry bureau, told Xinhua that 200 kilograms of the drug were strewn over 49,000 hectares last year and cost the bureau the equivalent of US$11,400.

There's been a slight drop in gerbil numbers since the program was started, Du said, with about 11 gerbils now caught for every 100 traps laid out. Previously, 12 gerbils was the average.

Contraceptive pellets have been mixed into bird feed in St. Paul, Minn., to help rein in that city's pigeon population, and officials in Los Angeles have used contraceptive injections on squirrels.

Animal rights groups often support contraception as a humane alternative to killing animals deemed pests.