By Ray Furlong BBC News in Prague

Police in Slovakia are investigating allegations of an attempt to poison the country's president, Rudolf Schuster.

Mr Schuster is in hospital in the capital Bratislava suffering from a mystery illness.

The allegation of poisoning was made by his son, Peter.

The president was taken to the central military hospital on Saturday with a high temperature, just hours after he had been released from the same hospital.

Sunstroke

His fever has since receded after strong doses of antibiotics.

Mr Schuster was first taken ill at a Mass celebrated by Pope John Paul II in Krakow last week, apparently suffering sunstroke.

Mr Schuster first fell ill at a Mass celebrated by the Pope in Krakow

Since then the diagnosis has changed and doctors now believe he may have a gall-bladder infection.

It is unclear who would want to poison the 68-year-old president.

Before his election in 1999 he was mayor of the eastern city of Kositsa, near the border with Ukraine, where he also served for many years as an official during the communist era.

Police seem to be taking the allegations seriously.

They have begun an investigation and tightened security around Mr Schuster.

Dramatic flight

He last fell seriously ill two years ago when he nearly died after suffering a perforated intestine.

On that occasion his life was saved after a dramatic last-minute flight to a hospital in Innsbruck in neighbouring Austria.

As a result of his current illness he did not attend a meeting of central European presidents in the Czech Republic last week, and a trip to Belgrade planned for next week has been postponed.