AMSTERDAM (Reuters) - Authorities in the Netherlands are preparing to evacuate two Dutch doctors who had unprotected contact in Sierra Leone with patients who later died of Ebola, a Dutch public health official said on Friday.

The two doctors have shown no symptoms of the virus but authorities believe there is cause for concern because they were not wearing full protective clothing when they came into contact with the patients, who had not yet been diagnosed with Ebola.

"The two doctors' personal protection should be considered inadequate. They could potentially have been exposed," said Jaap van Dissel, director of the Dutch Centre for Infectious Disease Control.

The two doctors will be evacuated on a special flight to minimise the risk of contagion to other passengers and monitored closely on arrival, according to media reports.

"It's only contagious if they have a fever," van Dissel said, and added that if symptoms developed, the two would be placed in quarantine in a university hospital.

Dutch public television said the case was discovered when the doctors came to the Netherlands' nearest embassy in Ghana after the patients they had been in contact with at the Lion Heart Medical Centre in Yele town died of Ebola.

The clinic, which normally deals with cases of malaria, which has symptoms similar to Ebola, has since been shut down by authorities in Sierra Leone.

More than 2,400 people have died so far from Ebola in West Africa since the outbreak started in March, taking a particularly heavy toll among medical workers, more than 120 of whom have died of the disease as of late August, according to the World Health Organisation.

(Reporting by Thomas Escritt; Editing by Sonya Hepinstall)