Increasing pressures on Britain's armed forces led Geoff Hoon to oppose major reinforcements in Afghanistan before UK troops left Iraq.
The former defence secretary, who served in the Ministry of Defence (MoD) from 2001 to 2005, told the Iraq inquiry the armed forces had been forced to rely on 'urgent operational requirements' for equipment.
He said his earlier experience dealing with British deployments in Bosnia and Kosovo had taught him the disadvantages of overstretching UK soldiers, who he found were simply "being rotated from one theatre to another".
"I didn't agree to it. I believed it was necessary to reduce our commitment in Iraq before taking on what was a Nato mission," he said.
"I felt that at that time, given our commitments in Iraq, it was probably better to participate in that mission until we were in a better position to do so."
Mr Hoon said he did not have any day-to-day difficulties securing funding from the Treasury, then headed by current prime minister, Gordon Brown.
The Liberal Democrats have been calling for the ex-chancellor to appear in front of the Iraq inquiry before the general election and redoubled their demands today.
"Once again we can see Gordon Brown's fingerprints all over this, but no sign of the man himself," foreign affairs spokesman Ed Davey said.
"He would have been instrumental in signing - or in some cases not signing - the cheques for military kit.
"The prime minister should appear before the Iraq inquiry before the election to give voters an informed choice. Instead we are being left with a huge Gordon Brown-shaped hole in the evidence."
The comments came at the end of what inquiry chairman Sir John Chilcot described as a "long day", in which Mr Hoon had earlier said Britain's policy on Iraq had been influenced by London's desire to remain on good terms with the United States.
Sir John has justified his decision to delay calling Mr Brown to the inquiry before the election on the grounds he does not want it to be politicised.
Tony Blair, his predecessor at No 10, will appear to give evidence on January 29th.