Iraqi Prime Minister Nuri al-Maliki Thursday pleaded for a major global effort to combat the "virus" of Al-Qaeda and terror networks, likening the fight to a third world war.

In Washington for a series of meetings hoping to drum up more support for Iraq, Maliki said that with US help his country had defeated Al-Qaeda.

But now with the vacuum created by the toppling of long-standing regimes during the Arab Spring, "the terrorists found a second chance."

His visit to the US comes as Iraq witnesses its worst violence since 2008, a surge in bloodshed that has killed more than 5,400 people this year despite several operations and tightened security measures.

"We want an international war against terrorism," Maliki said in a speech to the United States Institute of Peace, calling Al-Qaeda and its ilk "a virus" which was trying to spread "a dirty wind" around the region.

"If we have had two world wars, we want a third world war against those who are killing people, killing populations, who are calling for bloodshed, for ignorance and do not want logic to govern our daily lives."

Maliki also called for the convening of an international conference on counterterrorism to be hosted in Iraq, and his spokesman Ali Mussawi told AFP the idea had been "welcomed" by US officials.

"Maliki has received good responses, and everybody he has met has emphasized they will stand with Iraq, to help Iraq in fighting terrorism in Iraq and in the region," Mussawi said by phone from Washington.

Maliki also did not rule out running for a third term in elections due next year, but said it would be up to the Iraqi people.

His government has been criticized for not doing more to address grievances in the Sunni Arab community over alleged ill-treatment at the hands of the Shiite-led authorities.

But the Iraqi leader denied his country was plagued by sectarian unrest, pitting Sunni and Shiite Muslims as well as Kurds against each other, saying "all are targeted."

He blamed the terror groups for setting back Iraq's struggles to emerge from the dictatorship of Saddam Hussein and the bloodshed of the US invasion to rebuild its institutions, schools and homes.

"Without terrorism we would have leaped forward in providing services for our people," Maliki insisted.

"All our efforts should aim at preventing the success of Al-Qaeda and other terror organizations," he said, adding that while Baghdad was neutral in the conflict in Syria it was concerned militant groups might win control and gain a platform to wreak havoc across the region.

Maliki will meet US President Barack Obama on Friday at the White House to press for military equipment and greater cooperation in fighting militants.

"We expect the results of the visit will be very good and will improve bilateral relations, and it will lead to solutions," Mussawi said.

The United States vowed Wednesday to help Iraq combat terror groups, but said Baghdad needed a broader strategy which was not just based on strengthening its military arsenal.

The top US commander in the Middle East, General Lloyd Austin, gave voice to increasing concern in Washington that Al-Qaeda will manage to hunker down in a safe haven stretching from western Iraq into Syria.

"If left unchecked, we could find ourselves in a regional sectarian struggle that could last a decade," Austin told The Wall Street Journal in a rare interview.

"What we are very worried about is a continued downward spiral that takes you to a civil war," Austin said. "It could easily get worse."

The Iraqi leader also met Thursday with US Defense Secretary Chuck Hagel, who stressed "the important role that Iraq has in maintaining regional stability," Pentagon spokesman George Little said.