US Democratic presidential candidate Barack Obama met Iraq's prime minister yesterday to get a first-hand assessment of security in the country, where violence is at its lowest level since early 2004.

His visit thrusts US strategy in Iraq and troop levels to the centre of the November election race between the first-term senator from Illinois and Republican candidate John McCain. There are more than 140,000 US soldiers in Iraq.

Obama has called for the removal of US combat troops within 16 months of taking office should he win the election.