An investigation has been ordered into an "anonymous e-mail" claimed to be from a doctor complaining about serious problems in hospitals throughout Wales.
The complaint emerged on the day of Welsh Labour's manifesto launch
Liberal Democrats said they were sent the message and released it on the day of Welsh Labour's manifesto launch.
First Minister Rhodri Morgan said he must find out if the claims were true.
Plaid Cymru accused him of a "smokescreen" diverting attention from the NHS, and Conservatives said he should be ashamed of the situation.
Mike German, leader of the Lib Dems in the Welsh assembly, said he was sent the lengthy e-mail. His party released it on Thursday, hours before Labour unveiled its Welsh general election pledges.
The writer claimed to be a doctor who worked at accident and emergency units throughout Wales, where "day by day, week by week, the service that we are forced to provide for our patients worsens".
The e-mail described emergency departments as "third world, with patients waiting for more than 90 hours on hard trolleys for a bed, on a regular basis".
It said Welsh hospitals compared badly with England and there were "countless anecdotes of instances where patients' lives have been put at risk as a result of the current health policy of the National Assembly for Wales".
The BMA said A&E departments were under considerable pressure
Mr Morgan said the claims were serious and had to be investigated, although they were difficult to gauge because of anonymity.
Richard Lewis, Welsh secretary of the British Medical Association, also said it was hard to substantiate anonymous claims, but A&E departments were under considerable pressure.
Dr Lewis said: "We have been continually in dialogue with the Welsh Assembly Government to persuade them there are capacity issues and, while we acknowledge there have been improvements, GPs often still have no other option than to admit a patient to A & E."
The Royal College of Nursing said it was very concerned at the situation, and the problems depended on the number of patients arriving, while delayed discharges caused an "acute backlog".
The RCN said it would present a solution to the assembly government next week.
Mr German called the e-mail a "cry from the heart," and although the issue had been at the top of Labour's agenda when he raised it in January, it had since dropped from the agenda.
Plaid Cymru said: "This is just a New Labour smokescreen to divert attention away from the terrible crisis in the NHS. New Labour cannot use this to hide the fact that one in 10 of the Welsh population are waiting for treatment."
The Conservatives said: "This e-mail demonstrates the frustration of doctors and nurses working in the Welsh NHS today. Rhodri Morgan should be utterly ashamed of the situation he has created."