Hawaii (Reuters) - President Barack Obama Thursday summoned U.S. intelligence chiefs to a meeting next week to discuss how to prevent a repeat of the attempted bombing of a Detroit-bound airliner on December 25.

Seeking to quell criticism of his administration over an intelligence breakdown, Obama said he was briefed by his top advisers and would get assessments from intelligence agencies later Thursday and study them over the weekend before returning to Washington from Hawaii.

Obama had ordered an immediate review of what he called human and systemic failures that allowed the accused bomber, Umar Farouk Abdulmutallab, a 23-year-old Nigerian with alleged links to Islamic militants, to get on the transaTlantic flight from Amsterdam.

The incident has put Obama on the defensive, drawing charges from Republicans that his administration has dropped the ball on counterterrorism and exposing intelligence gaps that have lingered on since the September 11, 2001 attacks.

While still on vacation with his family in Hawaii, Obama appeared to be struggling to reassure the U.S. public and grab control of what has become one of his toughest national security challenges since taking office last January.

On Tuesday, in Washington, I will meet personally with relevant agency heads to discuss our ongoing reviews as well as security enhancements and intelligence-sharing improvements in our homeland security and counterterrorism operations, Obama said in a statement issued by the White House.

A preliminary report is expected to detail the intelligence lapses that allowed Abdulmutallab to board the Northwest Airlines flight to Detroit on Christmas Day with what authorities said were explosives sewn into his clothes.

The Nigerian suspect flew from Africa to Amsterdam, where he boarded the Northwest flight to Detroit.

ACCOUNTABILITY FOR MISTAKES

The report is also likely to make recommendations on improving the sharing of information between the United States' 16 intelligence agencies.

Obama, a Democrat, is under pressure from opposition Republicans, who fault his administration for not preventing the attack and the president for keeping silent about it for three days while on vacation in Hawaii.

Republicans portrayed Obama as weak on national security even as he campaigned for last year's presidential election, and have sought to push that point before mid-term elections in November, when they will challenge the Democrats' control of both houses of the U.S. Congress.

Admiral Dennis Blair, the director of national intelligence, said in a memo to staff that those who made mistakes in the incident would be held accountable.

The president was direct in his assessment that intelligence failures were a contributing factor in the escalation of this threat. This is a tough message for us to receive, he said.

In coming days we will review what information was available to whom, determine what mistakes were made in assessing or sharing that information, commend those who did their jobs well, and hold accountable those who did not.

I have no doubt in our ability to close the gaps that these attacks exposed, Blair said.

There was also strong speculation about a possible shakeup at the top of the intelligence community, which had information from interviews and clandestine intercepts but did not put the pieces together.

Intelligence lapses in the incident have raised questions about sweeping changes made to improve security and intelligence-sharing after the September 11, 2001, attacks.

A senior aide said Obama would seek accountability at the highest levels. Another official said the review would show where the dots should have been connected.

INTELLIGENCE TRAIL MONTHS OLD

U.S. intelligence and counterterrorism officials, speaking on condition of anonymity, said spy agencies picked up important information about Abdulmutallab, and about the intentions of al Qaeda leaders in Yemen, in the months before the attempted bombing.

The intelligence trail began at least four months ago, when the U.S. National Security Agency intercepted communications between al Qaeda leaders in Yemen discussing the possibility of using a Nigerian bomber, according to one official briefed on the intelligence.

The CIA first learned of Abdulmutallab in November, when his father came to the U.S. Embassy in Nigeria and sought help in finding him, a spokesman said.

The agency said it then worked with the embassy to add Abdulmutallab and his possible Yemeni contacts to the U.S. terrorism database and forwarded biographical information about him to the National Counterterrorism Center.

Although worrying, a U.S. intelligence official said the information the CIA received about Abdulmutallab was sketchy.

As authorities sought to piece together Abdulmutallab's movements, the Nigerian government said he began his journey in Ghana and spent less than 30 minutes in Nigeria's Lagos airport before boarding a flight to Amsterdam.

Although Abdulmutallab was known to have bought his ticket in Ghana's capital Accra, he had been thought to have started his journey on December 24 in Lagos, where he boarded a KLM flight to Amsterdam before transiting to the Detroit flight.

(Additional reporting by Adam Entous in Washington and Nick Tattersall in Lagos)

(Writing by Matt Spetalnick and Ross Colvin; editing by Paul Simao and Todd Eastham)

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