John Lennon's widow Yoko Ono and their son Sean Lennon on Wednesday launched "Artists Against Fracking" to oppose the technique for natural gas extraction in an important New York state water region.

"It seems that the city will be assaulted with dirty water," Ono, 79, told a press conference. "It's not fair for our children to ignore this."

Sean Lennon, 36, also attacked fracking, shorthand for the horizontal drilling technique which has opened vast new American gas supplies, but which opponents say risks polluting underground water sources.

Lennon urged the state authorities, who are expected soon to rule on whether to allow fracking in New York, not to believe the industry's assurances that it is safe.

"There is a campaign of misinformation telling the people that fracking is a clean alternative to coal," Lennon said. "Protecting our drinking water is fundamental to life."

"Artists against Fracking" also includes musicians like Lady Gaga and ex-Beatles Paul McCartney and Ringo Starr, as well as actors Alec Baldwin, Uma Thurman and writer Salman Rushdie.

New York sits over part of the Marcellus Shale, a formation that runs down through the eastern United States and is rich in deep natural gas deposits. Drilling has already started in other areas, including neighboring Pennsylvania.