More than a third of cell phones and portable chargers were found to have potential fire and electric shock hazards, the city's market watchdog warned yesterday.

The Shanghai Industrial and Commercial Administrative Bureau inspected 40 batches of cell phones and portable chargers sold at department stores, electric products outlets and markets in eight districts including Jing'an and Huangpu. Fifteen batches failed quality tests.

Three batches of mobile phones failed dielectric strength tests, meaning they carry a risk of causing an electric shock if their insulation systems lose power under certain voltages, threatening users' safety, officials said.

Two batches of mobile phones, made by Shenzhen Zhiyaotongxin Science and Technology Co and sold at the Jinyang Road branch of China Mobile Shanghai in Pudong New Area, were singled out for having serious quality problems.

They also failed conducted interference tests, which signifies that they will interfere with the normal operation of other electrical appliances and even the safety of the whole power network if the interference signal is strong, according to the bureau.

A similar problem was found with a batch of fake cell phones sold at the Wuwei Road outlet of Shanghai Dixintong Electronic Communication Technology Co.

Another batch of cell phones made by Shenzhen Xiaoyueliang Science and Technology Co and sold at Shanghai Xinyi Department Store was found to use a plug that did not meet national standards, which can lead to overheating resulting from poor contact, the officials warned.

Substandard portable chargers including a batch made by Vietnam Samsung Co were found to have discharge times that didn't correspond to what their labels indicated.

The bureau has ordered the stores involved to stop selling substandard products immediately and check their stocks thoroughly. Investigation is under way.

Editor: Mu Xu