Shanghai's consumer rights advocate demanded Monday that a major international chemical company apologize to Chinese consumers for issuing ultraviolet (UV) protection tags that ended up on substandard clothing.

Authorities accused the company, Switzerland-based Clariant, of disregarding its promise to consumers by failing to keep track of the tags, which are supposed to guarantee the clothing offers a certain amount of protection from UV rays.

Clariant makes a chemical used in sun-protective clothing. It sells the chemical to dyeing companies that incorporate it into the fabric they sell to clothing makers. Along with the chemical, it also sells the tags to show consumers that the clothing provides UV protection.

Clothing with the tags should have an Ultraviolet Protection Factor (UPF) of 30 or 50, according to tags presented by authorities.

However, consumer rights protection officials found that four brands of clothing carrying the tags failed to meet even the UPF 30 standard, according to the Shanghai Consumer Council, which met with a representative from Clariant Monday.

The company representative, Xu Jian, said that two of the tags were counterfeits, but admitted that the other two, which were attached to Dunlop and Nikko brands of clothing, were genuine.

Officials tested the clothing and it provided no higher than a UPF 20 standard of protection, the council said.

The tags represent a promise that Clariant makes to consumers about the quality of the product carrying them, said Fan Qiang, the director of the law department at the Shanghai Consumer Council. The company should live up to that promise.

Fan called on Clariant's headquarters to launch an internal investigation.

Xu said that Clariant has no idea which brands of clothing their tags finally end up on. "We sell the UV absorber chemical with the tags to the dyeing mills. We do not have any contact with the clothing manufacturers," Xu said.

The clothing manufacturers receive the tags from the dyeing mills. Clariant has no information about how many brands actually carry their tags.

The company dispenses at least 800,000 tags to the Chinese market each year, Xu said. They sell the tags for 0.3 yuan ($0.05) a piece.

The number of tags they dispense depends on how much of the chemical they sell and the amount of fabric the dyeing mills plan to make.

"We asked the dyeing companies to send samples of the dyed fabrics back to Clariant for testing," Xu said.

Still, the company has so far been unable to provide documentation showing that the fabric used to produce the substandard clothing was tested.