A US official has said that coalition air strikes have targeted a gathering of Islamic State leaders near Mosul in Iraq, destroying a vehicle convoy.
The official was not able to confirm reports that the IS leader Abu Bakr al-Baghdadi had been injured.
President Barack Obama has approved sending up to 1,500 more troops to Iraq, roughly doubling the number of US forces on the ground.
The White House said it would also ask Congress for $1.6 billion for a new "Iraq Train and Equip Fund" and billions more for operations to battle IS.
Pentagon spokesman Rear Admiral John Kirby said the funds would need to be approved before the first additional forces head to Iraq, which could happen within weeks.
Kirby added: "(Iraqi forces are) going on the offence now. And what this is designed to do is to help them continue to be able to do that, to improve their capability and their competence on the battlefield."
He stressed no American troops would take on combat roles.
Around 1,400 US troops are currently on the ground but the new authorisation gives allows the US military to deploy up to 3,100.
Barack Obama has authorised up to 1,500 more US military personnel to train, advise and assist Iraqi security forces, including Kurdish troops.
The personnel will conduct training missions in a number of military facilities within Iraq, the White House said.
Defence Secretary Michael Fallon has met with Iraq defence secretary Khaled al-Obeidi to discuss what Britain can do to assist the fight against IS.
Defence Secretary Michael Fallon said Britain is "stepping up" its military presence in Iraq, after announcing the deployment of extra military advisers to help train forces in the fight against Islamic State.
"We are going to be stepping up our training effort," Mr Fallon told the BBC.
"I can't give you precise numbers. I'm here to evaluate training needs and there are areas of expertise, particularly in counter-IED, roadside car bombs, where we can help from our experience in Afghanistan.
"So we will be putting in more training people to help at the training centres across the country, not just in the Kurdish areas."
The UK will send more military personnel to Iraq to help train forces to fight Islamic State, Defence Secretary Michael Fallon has confirmed.
Mr Fallon said advisers will be placed in training centres across the country, as he announced an expansion of UK involvement after a small team was sent to the northern city of Erbil last month.
Forces will offer further training to Iraqi soldiers and Kurdish Peshmerga fighters, including skills such as sharp-shooting and first aid.
But the Ministry of Defence insisted the move would not lead to the deployment of combat troops.
“It is right that we do more to help Iraqi forces take the fight to ISIL on the ground which is why the UK is offering the further training, support and assistance," Mr Fallon said.
British soldiers could return to Baghdad to support Iraqi security forces in their fight against Islamic State.
A number of officers are expected to be sent to join the US-led training mission to the Iraqi capital.
"We are exploring what more can be done on training as part of a future package of support aimed at bolstering the ability [of the Iraqi military] to tackle [Islamic State]," a senior defence source told The Times.
The Ministry of Defence is due to make an announcement later.
A car bomb in central Baghdad has killed at least three Shi'ite pilgrims, police and medics said.
Iraq's majority Shi'ites are preparing for the religious festival of Ashura, an event that has been marred by car and suicide bombings in the past.
British jihadists returning to the UK from Syria after becoming disillusioned with the extremists could be used to dissuade others from going to join the conflict, William Hague said.
The Leader of the Commons said authorities would be prepared to assist former-fighters, if satisfied as to their "good intentions".
His comments come amid reports that some Britons who left groups like Islamic State (IS) fear returning home in case they face arrest.
Speaking on BBC1's The Andrew Marr Show Mr Hague said:
Our top priority has to be the protection of the security of the people of this country, and that is why we will take action where we think people could be dangerous. But the Home Office and the police and the health service are also working together on what we can do to assist those people who come back with good intentions, but of course we have to be sure that they do have good intentions. We haven't had a lot of those people coming back yet and saying they want to be of assistance, but if they do well then of course the Government, the police, the National Health Service, will work with those people and help them to recover and to assist others.
US fighter and bomber planes launched five attacks against Islamic State (IS) militants near Kobani in Syria and five in Iraq since Friday, Central Command said.
The Kobani strikes "suppressed or destroyed" nine Islamic State fighting positions and a building, Centcom said. In Iraq, five air strikes destroyed an Islamic State vehicle southwest of Mosul Dam and hit four vehicles and four buildings used by militants near Al Qaim, it said in a statement.