U.S. counter-terrorism agencies are investigating whether an American-born Islamic cleric who has risen to become a key figure in the Al Qaeda affiliate in Yemen played a role in the attempted Christmas Day airplane bombing over Detroit, intelligence and law enforcement officials said Wednesday.

Intercepts and other information point to connections between terrorism suspect Umar Farouk Abdulmutallab and Anwar al Awlaki -- who also communicated with the accused U.S. Army gunman in last month’s attack on Ft. Hood, Texas, that left 13 people dead.

Some of the information about Awlaki comes from Abdulmutallab, the 23-year-old Nigerian charged with attempting to detonate a hidden packet of PETN explosive aboard a Northwest Airlines flight from Amsterdam to Detroit on Christmas Day, the officials said.

Under questioning by the FBI, Abdulmutallab has said that he met with Awlaki and senior Al Qaeda members during an extended trip to Yemen this year, and that the cleric was involved in some elements of planning or preparing the attack and in providing religious justification for it, officials said.

Other intelligence linking Awlaki to Abdulmutallab became apparent after the attempted bombing, including communications intercepted by the National Security Agency indicating that the cleric was meeting with “a Nigerian” in preparation for some kind of operation, according to a U.S. intelligence official.

Intelligence analysts did not realize the importance of that piece of information at the time because the name of the Nigerian was not included and the information was vague and lost in a flood of threat information coming in, the intelligence official said.

Awlaki, 38, emerged as a subject of intense interest and concern to the U.S. government after the Sept. 11 attacks, when authorities discovered he had been a spiritual leader of several of the hijackers while preaching at mosques in San Diego and the Washington, D.C., suburbs.

Born in New Mexico, Awlaki spent much of his life in the United States before moving to London to escape intense FBI scrutiny. He has been living in Yemen for at least five years, spending at least a year of it in custody.

Since his release, he has used Yemen as a safe haven from which to build his Internet site into a popular global forum to spread jihadist rhetoric and encourage attacks on Western interests.

The FBI has been investigating possible criminal charges against Awlaki stemming from his suspected attempts to spur extremists on to violence, including Maj. Nidal Malik Hasan, the alleged Ft. Hood shooter, an FBI official confirmed Wednesday.

But counter-terrorism officials say it was only recently that Awlaki forged close ties with the Yemen-based regional affiliate of Osama bin Laden’s terrorism network, known as Al Qaeda in the Arabian Peninsula.

And he has done so at a time when the group has stepped up its terrorist operations against U.S. targets in the region and far outside it. On Monday the group claimed credit for training and equipping Abdulmutallab with military-grade explosives for his suicide bombing mission. U.S. officials quickly corroborated the claim.

The two officials and others spoke on the condition of anonymity, saying they were not authorized to discuss the ongoing investigation or the classified intelligence-gathering effort against Awlaki.

Evan Kohlmann, a government counter-terrorism consultant, said Awlaki had been providing fatwas, or Islamic decrees, endorsing attacks by Al Qaeda in Yemen and playing a central role in its recruitment efforts, logistics, strategy and communications.

More recently, he said, Awlaki has been instrumental in negotiating alliances between the Al Qaeda affiliate and powerful Yemeni tribes that protect it from government crackdowns.

U.S. authorities are alarmed by Awlaki’s new role within the Al Qaeda affiliate not only because of those alliances and his influence on the Internet, but because of his familiarity with the United States, its customs and security measures, said the U.S. intelligence official.

“The concern is that now that they are more of a global threat, that he will use his knowledge of the United States to help them,” the intelligence official said. “Everybody is looking at that, certainly everyone in the intelligence community.”

The FBI official agreed, saying that while there is no reason to doubt them, Abdulmutallab’s claims are now being investigated intensively by counter-terrorism authorities on three continents as part of their probes into the Christmas Day attack and the escalating threat of the Al Qaeda affiliate to U.S. interests worldwide.

“He’s saying all this but we haven’t determined all of it is true; whether [Awlaki] blessed it or gave the green light or was the impetus behind it,” the FBI official said. “It’s very possible and it’s being investigated. But it’s also possible he’s saying it to give himself credibility” among militants who look up to Awlaki.

“What is certain,” the FBI official added, “is that we share the concern about Awlaki’s familiarity with the United States and the customs process, and that that could be something he’s sharing with others. He is the main subject in a major counter-terrorism investigation, so obviously the FBI considers him to be a serious threat.”

Rep. Jane Harman (D-Venice), chair of the House intelligence subcommittee, said Awlaki’s role in the Ft. Hood and Detroit cases raised serious concerns, as did his potential role in the regional Al Qaeda cell, which authorities say has direct links to Al Qaeda headquarters in Pakistan.

Harman said an airstrike last week against suspected Al Qaeda targets in Yemen may have killed Awlaki, but U.S. intelligence officials tell her they have not been able to confirm that. Some extremist websites have claimed that Awlaki is alive.

“Even if we were able to take him out last week, that doesn’t solve our problem,” Harman said. “There are others in Yemen who can do us great harm.”

The disclosures about Awlaki came as Harman and other lawmakers intensified their demands for more information about whether U.S. agencies had enough intelligence to thwart Abdulmutallab before he boarded the aircraft. The plane and its nearly 300 passengers were saved only because his attempt to detonate the explosives failed and he was subdued by passengers and crew, President Obama said Tuesday.

Obama said “there were bits of information available within the intelligence community that could have and should have been pieced together,” which would have allowed authorities to flag Abdulmutallab as he flew from Nigeria to Amsterdam and then Detroit.

Two ranking House Republicans sent a letter to Homeland Security Secretary Janet Napolitano with a list of 12 questions that they said needed to be answered. Many focused on suspected lapses in information-sharing.

The lawmakers also want a report on what actions were taken by the CIA and other intelligence agencies after Abdulmutallab’s father went to the U.S. Embassy in Nigeria in mid-November with concerns about his son’s radical extremism and ties to militants in Yemen.

In the Senate, a senior congressional official briefed on the U.S. intelligence community’s handling of the case said that the CIA did take appropriate steps to disseminate the information provided by Abdulmutallab’s father, but that there were growing concerns about how aggressively the information was investigated.

“I don’t see this as an information-sharing problem as much as not acting on information with enough urgency,” the official said. “Information can be available but it may not be acted on unless it meets certain thresholds. What does it take, how much information is needed, until action is taken?”

josh.meyer@latimes.com

Greg Miller in Washington and Sebastian Rotella in New York contributed to this report.