A decision on whether everyone should be on the organ donation register unless they opt out is due later.
The UK Organ Donation Taskforce – a government advisory committee – is expected to reject plans to introduce a system of “presumed consent”.
The prime minister and Chief Medical Officer believe it would tackle the chronic shortage of organs and save thousands of lives.
But the taskforce is likely to say it is too soon to change the law.
There are currently around 8,000 people in the UK who need an organ transplant but only 3,000 operations are carried out each year.
Evidence from other countries has shown that a system of presumed consent can improve the shortage of donor organs and can save lives
Tony Calland, British Medical Association
Earlier this year Gordon Brown said a presumed consent system had the potential to close the “aching gap” between the potential benefits of transplant surgery in the UK and the limits imposed by the current system of consent.
The British Medical Association back the idea of “soft” presumed consent, where family members have the final say – even if the patient has not opted out.
Any change to the system would involve amending the Human Tissue Act of 2004.
The medical profession is divided on the issue of presumed consent.
In September, intensive care doctors told the BBC they were deeply concerned about any radical changes to the law on organ donation.
Research by the Intensive Care Society suggests many specialists are worried that such a move would damage the trust between patients and doctors.
A report recommending a radical overhaul of the UK organ donor network in a bid to double the number of organs available for transplant, has already been published by the Organ Donor Taskforce, and is being implemented.
The latest recommendations on presumed consent are not binding and the government could decide to press ahead with changes to the legislation.
Health ministers in Scotland and Wales have suggested they are sympathetic to arguments in favour of presumed consent.
Dr Tony Calland, chairman of the BMA’s Medical Ethics Committee said: “The BMA hopes that if – as has been suggested – the Taskforce rejects the idea of a move towards a system of presumed consent now, it will not rule out future consideration of this option.
“Evidence from other countries has shown that a system of presumed consent can improve the shortage of donor organs and can save lives.
“The BMA supports a ‘soft’ system of presumed consent, where individuals who do not want to donate their organs have a formal mechanism for registering that objection and where families are consulted to identify any unregistered objection.”
Tim Statham of the National Kidney Federation said organs were being wasted because of a lack of capacity in the NHS – a situation which presumed consent would not solve.
Joyce Robins, co-director of Patient Concern, said: ‘We can only hope that Gordon Brown does not follow the example of the Welsh Health minister Edwina Hart, who rejected the all-party Welsh Assembly report when they decided against presumed consent after weeks of evidence and is still pressing ahead.”