But he's insisted if that doesn't happen we will go to war.
At his monthly news conference Mr Blair's been explaining what would make him support war against Iraq.
More troops on their way
UN inspectors have so far found nothing in their search for weapons.
Mr Blair says if they do the UN must approve a war against Iraq.
Thousands of American troops are on their way to join the 60,000 already stationed in the region.
And the British aircraft carrier Ark Royal has now left for the Gulf to support British troops there.