Ammon News - WASHINGTON (Reuters) - Among the consequences facing U.S. President Barack Obama if he decides against arming Syria's rebels is that Arab and European states may step in more aggressively, perhaps further fracturing rebel forces.

Having watched government forces seize the strategic town of Qusair from the rebels last week, Obama's senior national security advisers have held a series of meetings on what more, if anything, they are willing to do to help the opposition.

The fall of Qusair, signs that the military balance may be tipping in favor of President Bashar al-Assad, the entry of Lebanese Hezbollah fighters on his side, and the growing credence of allegations of chemical weapons use by the government have all triggered a re-evaluation of U.S. policy.

Next week's Group of Eight summit will give Obama a chance to discuss options with leaders of Britain, France and Russia and could influence any decision to arm the rebels or otherwise do more to support them.

Diplomats and analysts said if Obama chooses not to arm the rebels, or to take a more active role in coordinating the flows of arms and money from others, he may find states such as Saudi Arabia and Qatar pouring in even more money and materiel.

The danger, they said, is that this could accelerate a trend in which outside powers arm and fund preferred militants in Syria, creating client militias beholden to their patrons and undercutting efforts to develop a unified rebel front.

"If there is no (U.S.) decision this week, I think other actors will act. The Arabs can't afford to lose Syria," said a diplomat who spoke on condition of anonymity.

"If we don't act ... you're going to end up with Arab arms and Euro arms being provided," said Aaron David Miller, a former senior State Department official now at the Woodrow Wilson Center for International Scholars think tank in Washington.

"The logical consequence will be to accelerate the degree of ... dysfunction, the lack of organization that (already) exists among these groups," he added.

Arms and funding from Gulf Arab states have flowed to the Syrian rebels for months, while European states such as Britain and France have made clear they are considering doing so as well. Under their pressure, the European Union allowed its arms embargo to expire, freeing them to provide weaponry.

In Washington on Wednesday, British Foreign Secretary William Hague hinted at the possibility of doing more to support the rebels, although he did not provide details.

"We've met several times ... to coordinate our actions and our diplomacy and our support for the (opposition)," he said of the core "Friends of Syria" group, 11 nations including the United States and its European and regional allies.

"We will continue to do that, and we may well have to intensify that in various ways over the coming weeks and months in order to make it more likely that we can achieve a political solution in Syria," he told a news conference with U.S. Secretary of State John Kerry.

The United States has balked at giving weapons to the anti-Assad forces in part because of close links between some of the rebels and al Qaeda and the fear that the arms could end up being used against Western targets and U.S. allies such as Israel.

But Western diplomats said representatives would be meeting Free Syrian Army commander Salim Idriss - seen as a moderate who is trusted by U.S. officials - on Saturday in Turkey to discuss possible new aid.

U.S. MAY NOT MAKE DECISION THIS WEEK

The first hint the United States was revisiting its policy on Syria came with Kerry's decision to postpone a trip to Israel and the Palestinian Territories so as to stay in Washington and take part in meetings on Syria.

There are few signs, however, which way Obama may tip on the question of arming the rebels, playing a greater U.S. role in coordinating arms and money from others, or perhaps taking a more muscular position such as bombing Syrian military targets.

It is quite possible he may not make any decision this week, or indeed anytime soon. Two diplomats said they did not expect a decision this week and analysts suggested he may well hold off until consulting other major powers at the Group of Eight summit in Northern Ireland on Monday and Tuesday.

Senator Bob Corker, the senior Republican on the influential Senate Foreign Relations Committee, said on Wednesday he thought Obama would soon decide to arm and train the rebels, saying that was the best way to shift the balance of power on the ground.

"If I had to make a bet today, I believe that's what the administration is going to do over the next very short period of time," Corker said at a conference hosted by the Center for a New American Security think tank in Washington.

"If we can help shift that balance - again ... (with) no boots on the ground - but helping them in that way, I think we have a much greater opportunity for a negotiated exit, especially if Russia sees that occurring," he added.

FOCUS ON MEETINGS AT G8 NEXT WEEK

Obama has made no secret of his desire to avoid military entanglement in Syria as he has brought U.S. troops home from Iraq and is trying to wind up the U.S. war in Afghanistan.

The United States and Russia announced on May 7 they would try to bring the warring parties to a conference to implement a carefully negotiated peace plan they endorsed in June 2012 that left open the question of whether or not Assad must leave power.

With the fall of Qusair brought about by Syrian government forces and fighters from Lebanese Hezbollah, Assad seems to be gaining the upper hand on the battlefield, raising a serious question of why he would agree to any peace deal entailing his departure.

The United States wants the Russians to ensure that Assad sends a serious delegation to any peace talks, while Washington and its Arab allies will try to ensure that the civilian Syrian opposition, which remains splintered, also turns up.

Obama will see Russian President Vladimir Putin at next week's G8 summit and he could use the possibility of a more muscular U.S. role to try to win some kind of guarantee that Russia will produce a Syrian delegation ready to negotiate Assad's exit, assuming he may actually be willing to let go.

Conversely, if Obama continues to lean against the United States acting militarily to support the opposition, he may find himself forced to justify that stance to British Prime Minister David Cameron and French President Francois Hollande.