The announcement, on CNN, citing US government sources, will have caught most Croats by surprise; state-controlled Croatian television and radio were declaring only that the President was on holiday.
Mr Tudjman may have entered the Walter Reed hospital, where his defence minister and close ally, Gojko Susak, was recently treated, also for cancer.
Although the state of Mr Tudjman's health is a closely guarded secret, rumours have been spreading, following public appearances in which the normally sprightly 74-year-old has looked unusually drawn.
Mr Tudjman illness, if concerned, threatens to plunge the newly independent country into a leadership crisis, with worrying implications for the Dayton peace process in neighbouring Bosnia. Since winning the former Yugoslav republic's first multi party election in 1990, Tudjman has drawn power tightly into his own hands, a process consolidated by his stunning military victory in 1994 over the Belgrade-backed Serb rebels of the Krajina region.
There is no obvious successor and what worries Croats is the prospect of a potentially violent power struggle between moderates in Mr Tudjman's HDZ party under Vlatko Pavletic, the speaker of parliament, and ultra- nationalists under Vladimir Seks.
One of Seks' key allies, Ivan Milas, fuelled this concern when he made a veiled threat during last years parliamentary election campaign to call on the army and police if the HDZ were to lose the vote.Reuse content