By Peter Apps, Political Risk Correspondent

LONDON (Reuters) - As Syria's uprising escalates into outright civil war and begins to drag in other states, it risks fuelling not only wider regional confrontation but also growing antagonism between the world's great powers.

After months of largely peaceful demonstrations in the face of a bloody government crackdown, Syrian opposition fighters look to be behind an ever rising number of attacks on forces loyal to President Bashar al-Assad.

That in itself could mark the beginning of a long, bloody, open-ended civil war. And speculation about foreign military intervention could even spark a Cold War-style face-off between Russia and the United States.

Analysts and foreign governments have long said they believed Iran was providing military and logistics support to Damascus, and some now suspect the opposition too is now receiving foreign weapons.

That, many analysts fear, risks further fuelling the growing regional confrontation between Tehran and its local enemies, particularly the Gulf states and emerging heavyweight Turkey.

"The problem with conflict in Syria is that it is much harder to contain than what we saw in Libya," said Anthony Skinner, Middle East analyst for UK-based consultancy Maplecroft.

"It has much wider regional implications that have largely been ignored. It feeds into what is already happening in the Gulf, as well as elsewhere."

For now, the international action against Assad remains sanctions and diplomatic pressure. Syria's weekend suspension from the Arab League appears to have change little on the ground, and that raises the prospect of a more direct approach.

This week, Russian media reported that Moscow would be sending its flagship aircraft carrier to Syria. Officials talked down any link to recent events, but most analysts said it looked like a clear signal to Western powers in particular to back off.

Having watched as the United Nations Security Council resolution on Libya led to regime change, other emerging powers such as China also seem keen to draw a line in the sand.

Few expect a Libya-style military operation in the much more complex and militarily powerful Syria, but France has talked of creating some kind of "humanitarian corridor" perhaps protected by "armed observers." Turkey, which would likely have to be the primary provider of any foreign forces, has said it does not rule any scenario out.

SUPERPOWER CONFRONTATION?

Washington is believed reluctant to get involved. But the presence of one of its own aircraft carriers within striking distance of Syria has provoked speculation.

"The Russians are signaling that on Syria, it is not a situation where they will publicly protest but quietly and privately acquiesce," says Nikolas Gvsodev, professor of national security studies at the US Naval War College.

"The danger is that it is not clear what they are prepared to do to stop open intervention."

Outright military confrontation between the superpowers remained extremely unlikely, he said, but a worsening of relations would have real costs. Moscow has begun to talk increasingly tough on a planned U.S. missile shield in Europe, saying it would reengineer its nuclear ballistic missiles to pass through it if necessary.

"I think the Russians really were spooked by what happened in Libya and are determined to see that nothing like that happens again," said Nigel Inkster, a former deputy chief of Britain's Secret Intelligence Service (MI6) and now director of transnational threats and political risk at London's International Institute for Strategic Studies.

"In that they are joined by China and most of... the BRICs... (However) since there is clearly no appetite for a military intervention in Syria, the Russian navy's journey looks likely to be wasted."

A NEW MIDEAST BATTLEGROUND?

For many analysts, the real worry arising from Syria is the risk it could further supercharge existing tensions over Iran. Some believe Syria is already becoming the latest battleground in a largely hidden war raging across the region.

Whilst the Israeli media in particular continues to speculate on the prospects of a military strike on Tehran's nuclear program, most analysts believe such action remains unlikely.

Neither Israel nor the West has the military capability to destroy the nuclear program outright, many analysts say, whilst the potential for a devastating retaliation against oil targets in the Gulf could have devastating results for both sides.

Instead, many analysts believe what the region is seeing is a surge in covert action by both sides. That, they suspect, could explain both a string of recent "accidental" explosions at a number of Iranian nuclear facilities as well as a flurry of rocket strikes on Israel through perceived Tehran proxy groups.

The ratcheting up of sanctions and the storming of Britain's embassy there on Thursday by an angry mob all fit in to the wider picture, they say. So, too, does Syria, providing a potential incentive for Gulf states such as Saudi Arabia and Qatar to take a much more activist strategy to help any rebels.

"What you're seeing in the Middle East with the withdrawal of the U.S. from Iraq is Iran moving into an increasingly stronger position," said Reva Bhalla, director of analysis at U.S. private intelligence company Stratfor.

"If Assad survives in Syria, he will also be increasingly isolated and dependent on the Iranians, which will reinforce existing regional fears of Iran's growing influence."

Further stoking events, many believe, is a much wider tussle for power as the realization dawns that some two centuries of regional dominance by outside powers - first colonial Britain and France, then the U.S. - may be drawing to a close.

"We shouldn't be surprised that the Russians - in addition to the Turks and Iranians - feel like they've got an opportunity to expand their political-military influence in the eastern Mediterranean," said Thomas Barnett, U.S.-based chief strategist at consultancy Wikistrat.

"Nature abhors vacuums and so do rising great powers."

(Reporting By Peter Apps; editing by Andrew Roche)