The governor of Texas, Greg Abbott, has signed a bill into law that prohibits cities and towns from banning a gas drilling practice known as hydraulic fracking, giving the state sole authority over oil and gas regulation. Texas, a state that is home to the two of the most productive US shale oil fields, has been under pressure to halt an anti-fracking movement since November, when voters in the town of Denton voted to ban the gas extraction technique. “This law ensures that Texas avoids a patchwork quilt of regulations that differ from region to region, differ from county to county or city to city,” Abbott, a Republican, said. In fracking, a mixture of pressurized water, sand and chemicals is directed at rock to unlock natural gas. Operators say it is safe but many environmental groups call it wasteful, polluting, dirty and noisy. Fracking was pioneered at the Barnett shale natural gas formation in north Texas, which is where Denton is. Most of the crude output in Texas comes from fracked wells in the Eagle Ford and Permian fields to the south and west.