The Czech President, Mr Vaclav Havel, arrived back in Prague yesterday after cutting short a visit to Kuwait for health reasons.
An ambulance was waiting to take Mr Havel (64) to a military hospital, where he will stay for several days for tests, his spokesman said.
He told journalists at the airport that Mr Havel had not wanted to cut short the trip, but his advisers and doctor persuaded him to do so because of a persistent bronchial problem and several bouts of high temperature.
Since 1993 the Czech President has suffered a number of serious illnesses including bronchitis and pneumonia. He nearly died in December 1996 after an operation to remove a malignant tumour and one-third of a lung.
A former chain-smoker, Mr Havel was treated in hospital three times last year, once for a cold, once for aggravated bronchitis and once for a hernia.
In April 1998 he underwent emergency surgery on a ruptured intestine in Innsbruck and almost died of complications when doctors operated to remove his colostomy bag three months later.