WASHINGTON: The head of the US national counterterrorism center said Thursday the al Qaeda affiliate in Iraq is the strongest it's been since a peak in 2006.

Matt Olsen told a Senate committee hearing on the current terror threat to the US that al Qaeda in Iraq, also known as the Islamic State of Iraq and the Levant, has increased the pace of attacks this year.

''The group is exploiting increasingly permissive security environments in Iraq to fundraise, plan and train for attacks,'' Olsen said in testimony prepared for delivery.

Olsen did not say that al Qaeda in Iraq poses a direct threat to the US, and he noted it also continues to operate in Syria as one of the dozens of increasingly radicalised groups who have joined the original rebels seeking to overthrow the government of President Bashar Assad.

In 2006, the group was at its peak in Iraq when it bombed a Shia mosque and heightened sectarian killings.

Iraqi President Nouri al-Maliki was in Washington in October asking for more aid in the form of money, weapons and military trainers to help stem the violence.

Car bombings, shootings and other attacks in Iraq have been on the rise all year, intensifying fears that widespread sectarian conflict again may overwhelm the country. Widespread chaos nearly tore the country apart in the aftermath of the US-led invasion that ousted Saddam Hussein in 2003.

The bloodshed accelerated sharply after a deadly April 23 crackdown by security forces on a Sunni protest camp in a northern Iraqi town.

That set off near-daily attacks, mostly by Sunni extremists and al Qaeda militants determined to undermine the country's Shia-led government.

Al-Maliki warned in Washington that terrorists ''got a second chance'' to thrive in Iraq, largely as the result of the rise of al Qaeda fighters in neighboring Syria's civil war.

He said the world needs to help Iraq deal with its deadly insurgency.

On Thursday, a suicide attacker and twin bomb blasts targeted Shias marking Ashura, a somber religious ritual in Iraq, killing at least 41 people and wounding more than 100, officials said.

There was no immediate claim of responsibility for the latest attacks, but suicide attacks and other bombings, especially against Shias and Iraqi forces, are a favorite tactic of al Qaeda's local branch.