SHANGHAI - Shopping malls and office buildings in Shanghai are being urged to close on extremely hot days this summer to save power for residents' use in the midst of a shortage of supply, according to a recent notice issued by the Shanghai Municipal Electric Power Company.

The unprecedented power-rationing plan for 3,000 non-industrial users has been approved by the Shanghai municipal government but is not mandatory.

The Shanghai Municipal Electric Power Company is also calling on non-industrial users to set the temperature of their air conditioners above 26 C and says office buildings with power loads of more than 100 kilowatts may be asked to turn off their air conditioners for an hour on days when the temperature rises above 35 C.

On days when the mercury rises above 37 C, non-industrial users are being called on to shut to ensure there is enough power for residents.

In addition, as many as 24,000 electricity power users, most of which are industrial users such as factories, will be subjected to power rationing this summer. The number of affected users is higher than during any summer since 2003.

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Shanghai witnessed an annual growth in demand for power of 7 to 8 percent during the past three years and the gap between supply and demand this summer may reach 2.1 million kilowatts, according to the Shanghai Municipal Electric Power Company. The gap across the whole of China this summer may exceed 30 million kilowatts, according to the China Electricity Council.

Consumption of electricity by industrial users will be strictly limited during peak periods, while power rationing for non-industrial users will not be mandatory.

"We won't cut power off without notice and without the permission of users because the power rationing for non-industrial users is advisory and not compulsory," said Gu Weicheng, spokesman for the Shanghai Municipal Electric Power Company.

"We hope that non-industrial users will understand this plan and cooperate and we will guarantee the supply of power to residents."

Some non-industrial users, however, said they will not comply.

"We will refuse to be subjected to power rationing," said a clerk, who spoke on condition of anonymity, from the engineering department at Wanda Square, a major shopping mall in Shanghai's Yangpu district.

"We will take steps to save energy but we will not close because the financial loss would be considerable."

A notice about the shortage of electricity nationwide was issued by the National Development and Reform Commission.

However, rain in several areas of the country helped ease the power shortage because hydropower plants are now operating to their maximum. Meanwhile, demand for electricity for air conditioners fell because the air temperature also dropped.

For example, Zhejiang electricity authority announced on Saturday that power rationing in the province had been cancelled because the power shortage had eased in recent weeks, the Hangzhou-based Qianjiang Evening News reported.