Germany's federal environment ministry, as expected, has announced a planned moratorium on commercial hydraulic fracturing, or fracking above 3,000 meters depth until "at least" 2021.

Exceptions could be made for test drilling, said environment minister Barbara Hendricks.

The ministry said it will allow conventional fracking, using chemicals that pose no threat to water supplies, under strict conditions. Hendricks said Germany will implement the strictest rules that exist worldwide for unconventional gas exploration, as protecting drinking water and public health remain her "top priority."

The new regulations will be debated by the cabinet of Chancellor Angela Merkel later this month.