LONDON, April 17 (Reuters) - Health authorities in England have approved an 18.7 million pound ($31 million) investment to provide Gilead Sciences' controversial new hepatitis C pill Sovaldi for seriously ill patients.

Healthcare provider NHS England said the decision would benefit about 500 patients suffering from acute liver failure, many of whom are awaiting a liver transplant.

The recommendation means that while Sovaldi has not yet been approved by the National Institute for Health and Clinical Excellence (NICE), the country's cost-effectiveness watchdog, it will be funded for those patients at significant risk of dying.

NICE is due to publish its guidance on whether Sovaldi is worth using widely on the state-run National Health Service later this year.

Sovaldi is far more effective and better-tolerated than older treatments, but its high cost has provoked criticism from healthcare campaigners and insurers.

The current U.S. price for a 12-week course of treatment with Sovaldi is $84,000, or $1,000 for each once-daily pill, but Gilead has said the price in Britain will be about $57,000. ($1 = 0.5955 British Pounds) (Reporting by Ben Hirschler; Editing by David Goodman)