LONDON — British lawmakers opened a stormy debate on Tuesday about a proposed overhaul of the state-run National Health Service that has divided the ruling coalition and drawn criticism from the medical profession.

Critics fear the wideranging changes could be the first step on a slippery slope to privatisation of the NHS, a charge rejected by supporters of the bill who say it will better protect patients, boost choice and raise standards.

Conservative Prime Minister David Cameron was forced to pause the passage of the health bill through parliament in April and make amendments after it sparked widespread criticism.

Many in his junior coalition partners, the Liberal Democrats, were against it, as well as NHS professionals and patient groups.

The most controversial part of the proposals would see responsibility for commissioning services removed from local boards and handed to healthcare professionals, potentially widening the role of private providers.

Opening a two-day debate, Health Minster Andrew Lansley insisted changes had been made to safeguard against privatisation, saying the bill would ensure the NHS "is fit to face the challenge of tomorrow".

But Labour lawmaker Debbie Abrahams hit back, saying there were "many reasons why this bill is still a threat to the NHS".