MPs have urged the government to change the rules on organ donation.
There is a shortage of organs for transplant
Speaking in a debate in the House of Commons, some called for a system of "presumed consent" to be introduced.
Under this system, doctors would presume that patients agree to donate their organs when they die unless they have expressly stated otherwise.
MPs said the change would boost the number of organs available for transplant operations. However, the government rejected the move.
"We do not feel it is up to the state to dictate or presume that the state has a right to somebody's body, if an individual does not feel that is the right way forward," Health Minister Rosie Winterton said.
MPs said the government was missing an important opportunity to tackle the shortage of organs.
Former health secretary Kenneth Clarke called on ministers to be "more ambitious".
"We have the worst record of any part of western Europe and this weakness in our law should be addressed."
The Conservative MP said Spain had introduced presumed consent and had shown that it can increase the number of organs available for transplant.
He said the country had also shown that "presumed consent can be operated in a perfectly sensitive way".
Labour backbencher Tom Watson said he hoped ministers would change their minds on presumed consent.
Liberal Democrat health spokesman Paul Burstow said the move would help many people.
"I do not pretend that a system of presumed consent would solve the shortage of organs on its own," he said.
"But I think it should form part of a wider strategy to increase donation rates."
The MPs were speaking during a debate on the Human Tissues Bill. The proposed legislation aims to tighten up the rules on the retention of organs.
Under the plans, doctors will no longer be able to keep organs from dead patients without the full consent of their families.
It is being introduced partly in response to the Alder Hey and other scandals, where children's organs were taken without proper permission.
The Bill will also create a new body to regulate transplants and post mortems.
Ms Winterton said the proposals, which would apply in England, Wales and Northern Ireland, would make rules on organ retention clearer for doctors, patients and their families.