TIANJIN - Police in North China's Tianjin municipality have confiscated 600 Bitcoin mining computers after the local power grid reported abnormal electricity consumption.

Eight high-power fans were also seized, local police said on Tuesday, adding that it was the largest power theft case in recent years.

The power company monitored recent sudden increases in line loss on one electricity line, up to 28 percent at the peak. The phenomenon is usually closely related with increased load current.

An investigation found that the junction box of the suspected power user's electricity meter had been short-circuited - a typical way to avoid billing.

Bitcoin mining is a very power-consuming process which mainly depends on high-performance computers. The monthly electric charge of 600 such computers is estimated at hundreds of thousands of yuan.

Five people are under investigation and another has been detained.