Germany's environment minister said on Monday he did not want to make it easy for companies to start using controversial gas drilling methods, or fracking, dampening gas explorers' hopes of tapping new energy sources on their doorstep.

Pending rules for the modern drilling techniques would likely be tightened, said Peter Altmaier, a conservative politician in Chancellor Angela Merkel's government.

"The message is we want to limit fracking, we don't want to facilitate it," he told Deutschlandfunk radio. "And anyway I don't see in the foreseeable future that fracking will be employed anywhere within Germany," he added.

Fracking involves pumping vast quantities of water and chemicals at high pressure through drill holes, which together with vertical drilling helps prop open shale rocks to release trapped gas.

Altmaier said he would recommend that interested parties refrain from applying for exploration licences. So far, only a few small initiatives are under way in the absence of clear-cut rules.

The upper house of parliament, where Merkel's governing coalition no longer has a majority, earlier this month passed a resolution urging the cabinet to tighten rules for fracking, which critics say may increase seismic risks and even pollute drinking water.

Companies such as ExxonMobil and BASF's oil and gas arm Wintershall are pushing to explore possibilities but due to the country's federal structure, individual states can decide whether or not to issue permits.

In the United States, the new drilling technique has created a shale gas boom in recent years, freeing the country of the need to import, and changing gas flows and prices in the world market.

Germany produces only 14% of the gas it consumes and imports 40% from Russia.

Industrial gas consumers say they could benefit from fracking, as they need a secure supply at reasonable prices.

But opposition to unknown technologies is growing, and with a national election scheduled for Sept. 22, opposition parties and the government alike are seeking to avoid controversy.

Rules for initiatives to try and bury captured carbon from coal-fired power stations have already been watered down so much that the technology is practically dead in Germany.