SOFIA, August 11, 2008 (AFP) - Bulgaria's deputy health minister, Matey Mateyev, resigned Monday as a scandal over illegal bone marrow transplants at one of Sofia's main hospitals widened.

Mateyev said in a statement he was resigning in protest at his own ministry's decision last week to sack the head of Sofia's university Ivan Rilski Hospital, Rumen Stoilov.

The minister said he 'totally disagreed' with the sackings and said an 'unworthy campaign' was being waged against Bulgaria's leading neurosurgeons and their work in stem cell research.

'I stand behind the doctors at Ivan Rilski who have been working to develop new directions in medicine,' Mateyev wrote.

Hospital chief Stoilov and the hospital's entire board were dismissed Friday after an article in the daily newspaper, Trud, revealed that doctors at the hospital had been carrying out experimental stem cell transplants without the ministry's permission and without informing the patients that the operations were an experiment with no guarantee of success.

Instead of using bone marrow from donors, the doctors used the patient's own bone marrow.

The ministry said the operations had 'no chance of success'.

Patients with severe genetic and neurological diseases were offered the transplants as their last chance of treatment, but were not informed that the operations were only experimental, the Trud newspaper reported.

The head of the hospital's neurosurgical department, Ventsislav Busarsky, argued that such procedures were already being carried out in other countries.

There had already been media speculation last week that Mateyev might also be sacked in the affair, as part of the proceeds from the illegal bone marrow transplants were going to a medical laboratory partly owned by his 21-year-old son, Atanas Mateyev.

Bulgaria has had several scandals in recent months involving suspicious transplants or organ removals.