The militant Islamic leader, Abu Musab al-Zarqawi, has expressed virulent opposition to the election due to take place in Iraq next Sunday.
In an audiotape on an Islamist website, a speaker identified as Mr Zarqawi condemned the country's Shi'ite majority for supporting the election and urged the once-dominant Sunni minority to wage a holy war against it.
Zarqawi, who is an ally of the al-Qaeda group, has claimed responsibility for many bombings and beheadings in Iraq.
It is thought his comments are aimed at scaring voters away from the polls.
Separately, Iraqis living abroad are being given two more days to register to vote for the poll because of a low turnout.
The International Organisation for Migration, which is organising voting in 14 countries, said registration was being extended until Tuesday.
Just 130,000 Iraqis have so far signed up out of an estimated four million eligible overseas voters.
Iraq's interim government yesterday announced further security measures, including the closure of Baghdad airport for two days and overnight curfews in certain cities for the duration of voting.
