Mr Klestil's wife, Edith, left him earlier this month because of his relationship with Margot Loffler, a 39-year-old Foreign Ministry official.
'My private problems have not become easier,' he told the mass-circulation Neue Kronen Zeitung. 'But it's in my very own best interest to solve them quickly.'
Mr Klestil, a suave 61-year-old career diplomat allied to the conservative People's Party (OVP), was elected President in 1992, replacing Kurt Waldheim, whose term of office was overshadowed by allegations of wartime Nazi crimes. Despite his tainted past, Mr Waldheim served out his full term as head of state.
The office of President, although largely ceremonial, is highly respected by Austrians. One of Mr Klestil's promises on taking office was to repair the damage done to foreign relations by the Waldheim controversy.
Rumours of a split between the President and his wife went unreported by an unusually restrained press until Mr Klestil admitted last week that his wife had moved out after 37 years of marriage. A day later, photographs of Ms Loffler were splashed across front pages and state television reluctantly took up the story.
Ms Loffler, a graduate in Slavonic studies, served as a diplomat in Moscow and Bangkok in the 1980s. Now, with wild reports of a 'love nest' in the federal presidency, there are suggestions that she should quickly be given another foreign posting.
'Thomas Klestil must decide. Either he wants to enjoy private life with his female colleague or continue in office,' said Maria Graff, a member of the OVP Women's group. She said Mr Klestil had won the presidency by using his wife to portray himself as a happy family man, 'which was not true'.
'This was a dirty trick to play on the Austrian people,' Ms Graff said, adding that Mr Klestil should have resolved his 'hormone crisis' with his wife. 'Now to not divorce but carry on with the other woman, that's really low.'
Edith Klestil told Der Standard that her husband's adultery had become an unbearable embarrassment. The Klestils have three grown- up children. The eldest, Ursula, is two years younger than Ms Loffler.
Asked if a foreign posting for Ms Loffler would resolve the problem, Austria's first lady said: 'It would help.'
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