One third of the skirts sold at eight department stores including Jiuguang and Grand Gateway 66 checked by the city's market watchdog were substandard, involving international brands such as Longchamp and Max & Co, officials said on Thursday.

They failed for excessive formaldehyde, pH index, color fastness, fiber content, anti-pilling property and labeling, the Shanghai Industrial and Commercial Administrative Bureau said.

A total of 60 batches of skirts of 45 brands were tested and 20 failed, according to the bureau.

A batch of skirts branded Binkeke failed for excessive formaldehyde, and the skirts were sold at the Longemont Shopping Mall in Changning District, according to the bureau.

The content of formaldehyde of the skirts reached 374 milligrams per kilogram, compared with the national standard limit of 75 mg per kg, or nearly five times of the national standard, according to the bureau.

Excessive formaldehyde leads to allergic dermatitis and is harmful to health, bureau officials warned.

Another batch of skirts branded "Nice Claup" sold at the Jiuguang Department Store in Jing’an District had a pH index of 9.5, compared with the national standard between 4 and 8.5. Substandard pH index in clothing can cause skin allergies, leading to itching or pain, officials said.

Fourteen batches were substandard for unmatched fiber content. These included a batch of Longchamp skirts sold at Grand Gateway 66 in Xuhui District. The labeled materials of the skirts were rayon and polyurethane fiber, but it turned out to be nylon and regenerated cellulose fiber, according to the bureau.

The skirts did not bear the content of fiber as well, which was against the standard, officials said.

A batch of Max & Co skirts failed for fiber content as well.

The bureau has ordered involved businesses to stop the sales of substandard products immediately and check their stocks. Investigation is underway.