In a keynote speech at Westminster on his party's health policy, Mr Kennedy identified getting rid of waiting lists for diagnosis as a top priority.

He said that some patients had to wait for up to a year after being referred by a doctor before securing the tests and scans which established the nature of their conditions.

He believed that the Government was fixated on headline waiting times which recorded the time between diagnosis and treatment.

It was a scandal, he said, that the Government did not know the extent of diagnosis waiting lists, and had not published details.

"The Prime Minister loves to read out statistics that reflect well on his administration - particularly the fall in headline waiting lists. But such statistics tell us only part of the story, they don't tell us about people's real experience of the NHS."

Mr Kennedy said that research by the party's health spokesman Paul Burstow had established that in two out of five NHS Trusts, people wait six months or more for a MRI scan used to detect brain tumours, cancers and serious heart conditions, and around eight percent of NHS trusts had waiting times of over a year.

Mr Kennedy said: "This situation is replicated for patients waiting for all kinds of scans and tests across the NHS.

"It should be the policy of any party dedicated to our 'national health' to ensure that illnesses are diagnosed by the quickest route possible so that treatment can start soonest.

"It really is a scandal that after eight years in office this Government doesn't know the extent of these hidden waiting lists.

"It is not acceptable that the Government hasn't published the waiting times for these scans and tests, while focusing the efforts of the NHS on only one part of the process - which is only the waiting time after a patient has been diagnosed until they receive treatment."

Mr Kennedy said that a Liberal Democrat government would ask the Healthcare Commission to collect and publish test and scan waiting times.

The next step would be to put in place new systems to make the best use of available equipment, invest in diagnostic infrastructure, and boost recruitment of diagnostic staff.

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