BERLIN (Reuters) - German Chancellor Angela Merkel's conservatives and the center-left Social Democrats have agreed in coalition talks to put a moratorium on fracking for shale gas, leading members of the two parties said on Friday.

Ute Vogt, a Social Democrat (SPD) leader on environment issues in the talks, said that as a result fracking will not be possible in Germany before it is clear that the technology is safe. "We've agreed to a moratorium," she told reporters.

Shale gas fracking has so far been banned in Germany and the stance of the potential new government reinforces prospects that unconventional gas exploration will not be pursued in the country.

Katherina Reiche, a leader in Merkel's Christian Democrats (CDU), said the use of chemicals that could damage the environment should be banned.

Hydraulic fracturing, known as fracking, which involves pumping water and chemicals at high pressure thousands of meters below the ground to release gas from shale, has created an energy boom in the United States.

But it is criticized by environmentalists, who warn of potential seismic effects and water pollution. Opinion is split on whether to embrace it as a path to cheaper energy.

Due to environmental concerns, the previous center-right German government made up of Merkel's conservatives and the defeated pro-business Free Democrats had suspended plans to regulate fracking until after September's election.

Merkel's government had drawn up legislation laying out conditions for exploration and imposing restrictions on where drilling could take place, but that was put on hold.

If the moratorium is put in place, Germany will join countries including France in turning its back on the technology.

The government's stance determines whether oil and gas companies such as ExxonMobil and Wintershall get a chance to assess the potential of shale gas in Germany, which in the long run could use the resource to lower its dependency on gas imports that come mainly from Russia.

(Reporting by Erik Kirschbaum; Editing by Anthony Barker)