Iraq makes terror 'more likely'
Some 60% of people in 35 countries surveyed believe this is the case, against just 12% who think terrorist attacks have become less likely.
In most countries, more people think removing Saddam Hussein was a mistake than think it was the right decision.
Some 41,856 people were questioned in the poll for the BBC's World Service.
In 20 countries, there is overall support for US-led forces to withdraw from Iraq in the next few months.
Only in nine of the remaining 15 countries do more people believe US-led forces should remain until the situation is stabilised. Six countries are divided.
The removal of Saddam Hussein in 2003 is seen as a mistake in 21 countries, compared with 11 countries where more people view it as the right decision. Three countries are divided.
"It's official. Citizens worldwide think Western leaders have made a fundamental mistake in their war on terror by invading Iraq," says Doug Miller, president of the international polling firm GlobeScan, which carried out the survey.
"Short of the Iraqi government asking them to stay longer, people think the troops should leave," he says.
The countries most eager for US coalition withdrawal are Argentina (80%), Egypt (76%), China (67%) and Brazil (67%). Those which favour troops staying for the time being are the US (58%), Afghanistan (58%), Australia (57%) and Great Britain (56%).
However, the picture would be very different should the new Iraqi government ask US-led forces to remain until the situation was stabilised.
In that case, there is support in 21 of 34 countries for the coalition to stay.
Iraqis themselves are sharply divided over whether US-led forces should leave, with 49% favouring their removal and 49% favouring them to remain.
Support for troops staying rises only slightly, to 53%, if the Iraqi government requests it.
Iraqis are the most convinced that the removal of Saddam Hussein was right, with 74% agreeing with the move.
US President George W Bush has ruled out any hasty withdrawal from Iraq, saying the decision to will be made by military commanders, and not under political pressure