BERLIN (Reuters) - Germany should tread carefully in developing hydraulic fracturing, or fracking, to tap shale gas reserves, Chancellor Angela Merkel said on Wednesday, in some of her first public comments on the controversial drilling technique.

German Chancellor Angela Merkel (L) meets with Norwegian Prime Minister Jens Stoltenberg in Oslo February 20, 2013. REUTERS/Thomas Winje Oijord/NTB scanpix/Pool

Fracking has created a shale gas boom in the United States but it faces opposition in some European countries where critics say it could increase seismic risks and pollute drinking water.

“New deposits of gas could very probably be tapped in Germany with this technology but in contrast to the United States, we live in a very densely populated country,” Merkel told the Straubinger Tagblatt newspaper.

“We must look carefully at whether this technology can be used here. For me the most important thing is that there is no danger for people and the environment,” she said, calling for more national debate on the issue.

A strong environmental lobby is trying to put the brakes on fracking in Germany. Environment Minister Peter Altmaier, from Merkel’s Christian Democrats, has said he wants to limit fracking and ban it in areas where drinking water is protected.

Altmaier has said he would like to see a law in place before an election in September but it is unclear whether Merkel’s coalition partner, the pro-business Free Democrats, will agree.

Germany’s BGR Institute for Geoscience and Natural Resources has said 0.7 trillion to 2.3 trillion cubic meters of shale gas could be technically extracted. The bulk of that is located in north-western Germany.

Germany produces only 14 percent of the gas it consumes and shale could help mitigate the effects of dwindling reserves.

Fracking involves pumping water and chemicals at high pressure through drill holes to prop open shale rocks and release trapped gas.

Some companies, including ExxonMobil and BASF’s Wintershall unit want Germany to explore the options.

The opposition Greens, however, say Altmaier’s proposals do not go far enough to protect the environment and people.

“Altmaier has left open really important questions, such as the danger of earthquakes, the safety of drill holes and the disposal of poisonous liquid waste,” said Greens energy spokesman Oliver Krischer.

Fracking should not be used before all risks have been assessed and a legal framework set out, he added.

The U.S. shale boom has cut the country’s reliance on gas imports and changed gas flows and prices on the world market.