BERLIN (AP) — Germany's state-owned KfW bank is buying a 20 percent stake in electricity grid operator 50Hertz, fending off a bid from a Chinese company.

The economy ministry said Friday the decision was based on "security policy considerations," citing "a strong interest in protecting critical energy infrastructure."

50Hertz is one of four grid operators in Germany and supplies some 18 million people with electricity, mainly in the east of the country.

China's state owned network operator SGCC had tried to buy a stake in 50Hertz earlier this year. Belgian firm Elia, which owns 80 percent of 50Hertz, will buy the remaining stake and sell it on to KfW.

Separately, German media reported that the government plans to veto a Chinese takeover of specialist engineering company Leifeld Metal Spinning, citing security concerns.