DUBAI (Reuters) - Air strikes against Libyan Islamist militants that U.S. officials had said were staged by Egypt and the United Arab Emirates could mark an escalation of a regional struggle over the future of the Arab world.

Arab responsibility for the attacks would add to a picture of the West's regional allies acting increasingly independently in the absence of decisive U.S. involvement, seeking security goals with which Washington might not agree.

Egypt publicly denied involvement in the attacks on targets in its western neighbor and sensitivity over the strikes led to confusing statements from the administration in Washington.

U.S. officials told Reuters on condition of anonymity on Monday that the UAE had flown a series of strike missions from Egypt, and State Department and Pentagon spokespeople on Tuesday initially affirmed their understanding that Egypt and UAE were involved.

Later in the day the State Department backed off comments on Libya made at a regular briefing, saying they were "intended to refer to countries reportedly involved, not speak for them."

In a joint statement on Monday, the United States and its European partners Britain, Germany, Italy and France had urged outsiders not to interfere in Libya, which is suffering its worst violence since the overthrow of Muammar Gaddafi in 2011.

Tripoli residents said last weekend that unidentified jets had attacked targets in the capital. There were also strikes on Islamist-held positions last Monday.

Egypt formally denied conducting the air raids and UAE Minister of State for Foreign Affairs Anwar Gargash suggested on Twitter that the allegations had been promoted by anti-UAE Islamists.

Whoever carried out the raids, they were in tune with wider efforts by Egypt and conservative Sunni Muslim allies to roll back the influence of the Muslim Brotherhood - a regional Islamist movement - and its sponsor, Qatar.


POLICIES, VALUES

Analysts noted that U.S. President Barack Obama, who last year called off air strikes on Syria at the last minute, has himself said allies in the region should play a greater role in tackling local crises.

"In the light of U.S. inaction in Syria, the message is clear, that you have to take care of your own concerns," said Emirati political scientist Abdulkhaleq Abdulla, stressing that he did not know for sure if the UAE was involved or not.

If the raids were indeed carried out by Egypt and the UAE, it would open a new chapter in inter-Arab relations, said Theodore Karasik, research director at Dubai think tank INEGMA.

"The feeling is that America hasn't stood up for its values and policies in the region," he said, referring to a common Arab view that the U.S. administration has been hesitant in supporting rebels fighting Syrian President Bashar al-Assad.

"So these states will now take it upon themselves to act. Ironically, this is, in broad terms, what Washington has been asking them to do - solve their own problems."

The alleged use of outside military muscle touched a nerve in the West, acutely aware that its own intervention in Libya in the run-up to the fall of Gaddafi contributed to the country's descent into chaos.

In an indication of the sensitivity of the issue, the publication of their assertions was followed within hours by a joint statement by the United States and European allies cautioning against foreign interference.

Outside involvement would worsen divisions in Libya and slow progress in its political transition, it said.

And yet the West may have to get used to a more activist stance by participants in a tussle for influence pitting Egypt and most of the conservative Gulf Arab states against Islamist-friendly Qatar, Sudan and non-Arab Turkey and Iran.