Al-Qaeda in Iraq's public boasting of its role in spawning and supervising Syria's Al-Nusra Front could backfire on the jihadist rebel group's support on the ground, analysts say.

The announcement, in an audio message posted on jihadist forums, confirmed widespread suspicions of links between the two organisations, both of which are blacklisted as terror groups by Washington.

But the move could undermine support for Al-Nusra Front, or Jabhat al-Nusra in Arabic, which has been credited with playing a major role in rebel gains against forces loyal to Syrian President Bashar al-Assad, analysts told AFP.

"This could potentially hurt Jabhat al-Nusra within the country, which would then affect the insurgency on some level," Aaron Zelin of the Washington Institute for Near East Policy told AFP.

"Jabhat al-Nusra has got a really good reputation in the country, and the name Al-Qaeda is discredited throughout most of the Muslim world at this point.

"Do people not remember what the guys in Iraq did five years ago?" he asked, referring to the group's reputation for brutality to civilians during the height of Iraq's bloody sectarian conflict.

Both groups have achieved notoriety for their use of suicide attacks and car bombs, as opposed to the more conventional warfare of other insurgent factions in Iraq and Syria.

But Al-Nusra had appeared to have learned from mistakes made by Al-Qaeda in Iraq, in particular by insisting that its targets were military or part of the regime apparatus, even though they have often caused civilian casualties.

Islamism specialist Cole Bunzel said that the open admission that Al-Nusra was not a Syrian-born organisation but a creation of Al-Qaeda in Iraq appeared to be a strategic blunder.

"It emphasises the fact that Jabhat al-Nusra is a foreign entity, and it is Al-Qaeda," said Bunzel, a PhD candidate at Princeton University.

"No longer can Jabhat al-Nusra, or what it's now called, gloss that over, or deny that connection.

"Strategically, it doesn't seem to make a lot of sense, but at the end of the day, Jabhat al-Nusra is what it is," said Bunzel, who wrote a detailed post analysing the announcement for the Jihadica blog.

"What it is, is Al-Qaeda."

According to Donald Holbrook of St. Andrews University's Centre for the Study of Terrorism and Political Violence, Al-Qaeda believes it has "gone into a quagmire in Iraq, largely of their own creation."

And so, with the latest announcement, "they're trying to seem relevant, they're trying to seem in control, they're trying to engage in a jihad which is seen as legitimate, which has at least a semblance of some sort of popular support."

While the announcement has largely been met with support on jihadist Internet forums, there has been some criticism of the decision to openly link the two groups.

In a Facebook post shortly after the announcement, Abu Baseer al-Tartusi, a well-respected adviser to the Syrian Islamic Front, a militant group that, though not as radical as Al-Nusra is still regarded as hardline, said it could lead to infighting among rebel groups and give pro-Assad forces a rallying cry.

"The biggest losers from this announcement are the oppressed and violated Syrian people, and their blessed, orphaned revolution," he wrote.

The linking of Al-Qaeda in Iraq to Al-Nusra could also give backing to repeated warnings by Iraqi Prime Minister Nuri al-Maliki of the dangers of a spillover of violence across the two countries' 600-kilometre (375-mile) border.

Iraqi political analyst Ihsan al-Shammari said that while Maliki was unlikely to change policy towards Syria, the announcement would help him "convince international and domestic opinion, to understand there will be repercussions within Iraq."

"It will strengthen his argument about the fears he has described," Shammari said.