CONTROVERSIAL fracking operations at a site in Lancashire have been hit by another technical problem — the latest in a series of failures to safely and successfully extract shale gas.

The company has repeatedly tried and failed to use cement as part of the sealing of “sleeves” deep underground, where a toxic mixture of chemicals, sand and water is pumped into shale layers to fracture them to release trapped gas.

The cement aims to shut the sleeves, which should be movable, after they became stuck in an open position.