Former Croatian Prime Minister Ivo Sanader has quit the country amid a corruption inquiry, but reportedly denies fleeing from prosecution.
Mr Sanader, now an independent MP, crossed the border into Slovenia hours before parliament voted to lift his immunity from prosecution.
Investigators have been focusing on officials from the ruling HDZ party who were in office under Mr Sanader.
Brussels has put pressure on EU-hopeful Croatia to stamp out corruption.
Mr Sanader was in power from 2003 until he stepped down in July 2009 in a surprise move.
He was expelled from the HDZ in January but carried on as an independent MP, and so he still enjoyed immunity from prosecution.
But all 104 parliamentarians present at the vote chose to lift his immunity.
The BBC's Balkans correspondent Mark Lowen says Mr Sanader has been linked to corruption allegations involving the Austrian bank Hypo, and he is the highest-profile politician in the country to be facing investigation.
'I am on a trip'
The former prime minister crossed into Slovenia on Thursday, the interior ministry said, adding that police had had no legal reason to stop him.
Croatian newspaper Vecernji List contacted him to ask if he was "on the run", and whether he would respond to a summons issued by anti-corruption investigators.
"I am on a trip, planned beforehand and of course I will respond," he was quoted as replying in a text message.
On Monday, former Defence Minister Berislav Roncevic, who served in Mr Sanader's cabinet from 2003 to 2007, was sentenced to five years in prison for corruption on Monday.
Since Mr Sanader's departure from office, a dozen managers of banks and state companies have been arrested for corruption but in most cases indictments are still pending, Reuters news agency reports.