Dead patients in British hospitals could soon have their organs removed without doctors needing explicit consent to help save the lives of thousands of people needing transplants.

Prime Minister Gordon Brown has backed the plan, saying he hopes a new organ donation system could begin as early as this year.

The proposed "presumed consent" system would be modelled on a similar program in Spain and allow organs to be removed unless a person had specifically opted out of the national register or their family objected.

The government hopes the change, which some patient groups oppose, will help overcome an acute shortage of organ donors and rise in unnecessary deaths in Britain, which has one of the lowest rates of donations in Europe.

Mr Brown, who carries a donor card, said he wanted to start a "genuine debate" on the issue and that if changes were introduced the government would ensure strict safeguards were in place.

"A system of this kind seems to have the potential to close the aching gap between the potential benefits of transplant surgery in the UK and the limits imposed by our current system of consent," he wrote in The Sunday Telegraph.

"Many of us will have friends and family members who have benefited from transplant surgery, or - tragically - who have endured the agonising wait for a life-saving organ that did not become available in time.

"That is an avoidable human tragedy we can and must address."

But watchdog group Patient Concern spokeswoman Joyce Robin said she was appalled by the possible overhaul of the current donation system and the government should do more to encourage people to register as donors.

"They call it presumed consent, but it is no consent at all," she told the newspaper.

"They are relying on inertia and ignorance to get the results they want."

More than 8,000 patients in Britain are currently waiting for an organ donation but only about 3,000 transplant operations go ahead each year.

Nearly 15 million people are listed on the nation's organ donation register.