The Iranian military smuggled new deadly munitions to its allies in Iraq and Afghanistan in recent months in order to to accelerate the US withdrawals from these countries, The Wall Street Journal reported late Friday

Citing unnamed US officials, the newspaper said the Islamic Revolutionary Guard Corps has supplied its allies with rocket-assisted exploding projectiles, which have already killed American troops.

The officials said Iranians had also given long-range rockets to the Taliban in Afghanistan, increasing the insurgents' ability to hit US and other coalition positions from a safer distance, the report said.

"I think we are likely to see these Iranian-backed groups continue to maintain high attack levels," Major General James Buchanan, the top US military spokesman in Iraq, told The Journal. "But they are not going to deter us from doing everything we can to help the Iraqi security forces."

Violence killed more Iraqis last month than at any time since September, figures showed on Friday after the US reported deaths that also made June the deadliest month for its troops in Iraq for three years.

The Baghdad government blames Al-Qaeda for most of the 271 deaths of its citizens last month, while the US military accuses Iranian-backed Shiite insurgent groups for the attacks that killed 14 Americans.

Data compiled by the health, interior and defence ministries showed that 155 civilians, 77 policemen and 39 soldiers died in attacks last month, 34 percent more than the 177 killed in May.

The majority of American troops killed in June died in rocket attacks against military bases, or by roadside bombs that targeted their convoys.

Last month's toll was the highest since June 2008, when 23 American soldiers were killed, at a time when US forces were directly involved in fighting insurgents.