The sources did not identify who Hasan contacted but described them as Islamists associated with and sympathetic toward al Qaeda.
Thirteen people were killed in the shooting at the Fort Hood Army post by the suspected Hasan, a Muslim born in the United States of immigrant parents.
The New York Times said intelligence agencies intercepted communications last year and this year between Hasan and a cleric in Yemen known for his incendiary anti-American teachings.
It is unclear what federal law enforcement authorities did with the intelligence information. One intelligence official said: “There’s no sign at this point that the CIA had collected information relevant to this case and then simply sat on it.”
The Justice Department, the FBI and the Army had no immediate comment about having received any intelligence information about Hasan before the shooting.
In a letter to Director of National Intelligence Dennis Blair and the heads of the FBI, the CIA and the National Security Agency, Representative Pete Hoekstra, the ranking Republican on the House Intelligence Committee, has asked intelligence agencies to preserve the information they have on Hasan.
“I believe members of the full committee on a bipartisan basis will want to scrutinize the intelligence relevant to this attack, what the agencies in possession of that intelligence did with it, who was and wasn’t informed and why, and what steps America’s intelligence agencies are taking in light of what they know,” Hoekstra said in a statement.
How US agencies acted
Hoekstra’s comment was reminiscent of questions asked after the Sept. 11 attacks, when there was deep soul-searching and recrimination in Washington over how US intelligence and law enforcement agencies failed to prevent the hijacked plane attacks on the World Trade Centre and the Pentagon.
Wendy Morigi, Blair’s spokesperson, said: “The intelligence community is carefully following every lead and examining all information regarding Army Major Nadal Hasan.”
“Director Blair has been in communication with the leadership of the congressional intelligence oversight committees and will ensure there is a full accounting of the facts,” she added.
The shooting spree took place last Thursday at Fort Hood’s crowded Soldiers Readiness Processing Centre, where US troops were getting medical checkups before leaving for foreign deployments.
Hasan, 39, had spent years counselling severely wounded soldiers at the Walter Reed Army Medical Centre in Washington, many of whom had lost limbs fighting in Iraq and Afghanistan.
He was transferred to Fort Hood in April and was to have been deployed to Afghanistan, where the .S military is engaged in an increasingly bloody war against Taliban and al Qaeda fighters.
Hasan yelled “Allahu Akbar” Arabic for “God is Greatest” just before the shooting, Chuck Medley, Fort Hood’s director of Emergency Services, said.
But the Fort Hood commander, Lieutenant-General Robert Cone, said there was no evidence this was a terrorist attack.
American Muslim groups expressed regret and stressed that the incident appeared to have been carried out by a single disturbed individual.
Fort Hood, about 60 miles (97 km) from the state capital Austin, is home to about 50 000 troops.