Three suicide car bomb attacks against offices in a Kurdish-controlled Iraqi town killed at least 25 people on Sunday, most of them Kurdish forces veterans volunteering to re-enlist, officials said.

"At 10:30 this morning (0730 GMT), three car bombs struck Qara Tapah," said Mayor Wahab Ahmed, who was lightly wounded in the attack.

Qara Tapah lies close to Jalawla, a key battleground northeast of Baghdad between pro-government forces and Islamic State group (IS) jihadists.

The mayor said the three car bombs targeted his office, a building used by the Kurds' asayesh internal security service and an office of the Patriotic Union of Kurdistan party.

Ahmed said nearby buildings used by the electricity department and the Kurdish peshmerga forces' veterans affairs bureau were also seriously damaged in the explosions.

A high-ranking security official in the autonomous Kurdish regional government put the death toll at 27 and said most of the dead were peshmerga veterans who had volunteered to return to active duty to fight IS.

"Twenty-four of the victims are peshmerga veterans," the official said, speaking on condition of anonymity because he is not authorised to talk to the press.

"They had come to join the front against IS. There are still victims trapped in the debris," he said.

A local federal army official could confirm 25 deaths.

Confessionally and ethnically mixed Diyala province, which borders Iran, has seen intense fighting pitting militants of IS against Iraqi federal troops, and their Kurdish and Shiite militia allies.

In the provincial capital Baquba Sunday, a roadside bomb blast in a busy neighbourhood called Al-Dhabbat killed six civilians, a police captain and a doctor at Baquba hospital said.

It was not immediately clear who the explosion targeted.

A woman was killed and two children wounded when another bomb targeted a policeman's home in Baquba's Shifta neighbourhood, the same sources said.

US drops food, ammunition to embattled Iraqi troops
Washington (AFP) Oct 11, 2014 - US military aircraft have delivered food, water and ammunition to besieged Iraqi troops battling Islamic State militants, the Pentagon said Saturday, as the coalition pursued its air assault in Iraq and Syria.

The move marked the first time that coalition aircraft airdropped supplies to Iraqi government forces. Similar drops were previously part of humanitarian missions for civilians, such as Yazidis and Turkmen.

The airdrops of vital supplies to troops in northern Iraq on Friday and Saturday came at Baghdad's request, US Central Command said in a statement.

"US military forces conducted multiple airdrops in Iraq in the vicinity of Baiji... to resupply Iraqi security forces operating in the area," it added.

In total, 36 bundles containing 7,328 halal meals, 2,065 gallons of water and 16,000 pounds of ammunition were dropped.

While Baiji remains under Baghdad's control, nearby towns "are contested as ISIL continues to conduct operations in the area," the statement said, using another acronym to identify the IS group.

The embattled Iraqi army is facing increasing pressure from IS jihadists in several hotspots.

The airdrops come after US Defense Secretary Chuck Hagel described the campaign against IS in Iraq as "difficult," particularly in the western province of Anbar.

"Anbar province is in trouble. We know that," he said on Friday during a visit to Colombia.

"This is a difficult effort. It is going to take time. It won't be easy. So, yes, there is a lot of uncertainty in Anbar right now."

The US-led coalition also launched fresh air strikes in Iraq and Syria on Friday and Saturday, Central Command said.

Bomber and fighter jets conducted six air strikes in Syria, including four in the battleground town of Kobane near the Turkish border.

In Iraq, three air strikes were carried out by attack and fighter jets -- one in Tal Afar in the north and two in Hit in Anbar province -- with the help of Dutch aircraft.

A US-led coalition has been conducting air strikes in Iraq since early August and in Syria since mid-September.

IS fighters have beheaded four Western hostages and seized huge swaths of territory in Iraq and Syria.