The White House said on Wednesday that US President Barack Obama on Wednesday approved the deployment of 450 more US military trainers to Iraq.

The White House said on Wednesday that US President Barack Obama on Wednesday approved the deployment of 450 more US military trainers to Iraq that will join an already 3,100-strong mission to "train, advise and assist" the Iraqi army and tribal fighters.

The new contingent will focus on efforts to wrest back control of provincial capital Ramadi, which was seized in May by the so-called 'Islamic State of Iraq and the Levant' (ISIL).

Obama has ruled out putting combat troops on the ground, fearing it may re-entangle US forces in a war he fought hard to end.

Instead his administration has offered air support, arms and training to an amalgam of disparate Iraqi forces.

In addition to extra trainers, the White House announced there will also be "expedited delivery of essential equipment and material" for those tribal and Kurdish Peshmerga fighters -- in coordination with the central government in Baghdad.

While senior Obama military and civilian aides indicate he "hasn't ruled out any additional steps," such as providing field advisers or personnel to call in airstrikes, they say the current strategy will remain in place.

"The president has made it clear that he will look at a range of different options," said Deputy National Security Advisor Ben Rhodes.

"Our overriding focus here is making sure that there is Iraqi capacity on the ground."

The new US training contingent will be based at Taqaddum Air Base, perched between takfiri-held Ramadi and Fallujah.

The Pentagon said a large portion of the new US troops will focus on protecting trainers and other officials, while a small group will help Iraqi forces plan helping the Iraqis plan an eventual counter-attack on Ramadi.