Taiwan's President Chen Shui-bian has pledged not to declare independence from China if he is re-elected.
Chen has called both polls on the same day
His decision to call a referendum on security issues and whether or not talks should be restarted with Beijing has angered the mainland.
China regards Taiwan as a breakaway province which should be reunited with the rest of the country.
President Chen is standing for re-election next month, and the referendum will be held on the same day.
The president faces a tough battle for re-election, lagging behind his rival Lien Chan in opinion polls.
But he began to close the gap with his Nationalist party rival after he called the referendum for the same day as the presidential vote.
The Taiwanese people will be asked to approve an increase in military spending, and to sanction attempts to reopen talks with Beijing.
The move has angered the Chinese leadership, which fears the referendum will set a precedent and in future the mechanism could be used to try to force a vote on independence.
The referendum has been criticised by the United States, France and Germany among others as a threat to the status quo.
Now in what seems to be an attempt to soothe international concerns about his intentions, the Taiwanese president has renewed a promise he made before the last election that he would not declare a permanent split from China, a move that Beijing has always made clear would lead to war.
Perhaps though with an eye to his pro-independence supporters, he made clear that in any case he already considered Taiwan independent.
He also said the island would press ahead with plans to buy anti-missile systems from the US, even if the referendum rejects the call to boost the island's defence spending.
The arms package was sanctioned by President George W Bush three years ago, and was the largest for Taiwan in a decade.