The Iranian economy is finding it difficult to cope with the economic sanctions, but the extensive financial aid to Syrian President Bashar Assad has not stopped – and is creating a rift at the top of the Iranian regime.

The London-based Times newspaper reported Monday that Tehran has transferred some $10 billion in support of Assad's war against Syrian rebels. Western intelligence sources say the failure to decide the Syrian conflict in favor of Assad has caused a split between Iranian supreme leader Ayatollah Ali Khamenei and Iran’s spymaster in the past 14 years, Qassem Suleimani.

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According to the report, defectors from Assad’s forces have told coordinators for the rebel Free Syrian Army in the Gulf that Iran has been paying the salaries of Syrian government troops for months, as well as providing weapons and logistical support.

This huge outlay of $10 billion has increased friction in Tehran as the Iranian economy labors under international sanctions imposed by the West to curb Iran’s nuclear program.

Suleimani, the commander of the Quds Force, a unit of Iran’s Revolutionary Guard, masterminds Iranian strategy with its proxies across the region, including Hezbollah and Hamas.

“Suleimani promised Khamenei that he would turn the situation in Syria around and has failed to deliver,” a Western defense source told The Times.

Instead, the conflict has become a bloody stalemate, with Iran pumping weapons, troops and cash into Syria to counter support for the rebels from Saudi Arabia, Turkey and Qatar, overseen by the US.

According to the report, senior regime figures are also questioning Iranian strategy in Syria, fearful of unrest at home if the conflict drags on and the scale of Iran’s spending becomes public.

Rial plunges 13% to new record low

Iran is seemingly reiterating its support for Assad. Ali Akbar Velayati, Ayatollah Khamenei’s foreign policy advisor, insisted over the weekend that victory for the Assad regime was “certain” and would represent a victory for Iran.

But behind the scenes, The Times says, Iran is exploring other options, reopening talks with various opposition groups, including the Syrian Muslim Brotherhood, in an effort to retain a stake in the country should the Assad regime be toppled.

“They need time to build the necessary alliances to make sure that Iran is not expelled from Syria forever,” a defense source in the Gulf told the London-based newspaper.

According to the report, failure to crush the Syrian uprising puts the first real dent in Suleimani's reputation. Head of the Quds Force since 2002, he marshaled the Shia insurgency against US-led forces in Iraq, entering Baghdad at will under the noses of the Americans and becoming a darling of the ultra-conservative elite in Tehran.

He is so close to Ayatollah Khamenei that he has been touted as a contender for the presidency when Mahmoud Amhadinejad steps down next year, but most observers consider him unlikely to run for office just now.

With the Syrian conflict unresolved, the wider Middle East in flux and the mounting threat of an Israeli attack on Iran’s nuclear facilities, The Times says, Ayatollah Khamenei will probably conclude that Suleimani would better serve Tehran in his present role.

Meanwhile Monday, Iran's currency, the rial, crashed more than 13% in trade on Monday to a record low of 33,500 to the dollar, according to the Mesghal.com exchange tracking website.

The dramatic freefall added to more gradual losses in past months that have seen the rial lose more than three-quarters of its value compared with the end of last year, when it was at 13,000 to the dollar.

Iran is suffering heightened geopolitical tensions over its nuclear programme and the effects of draconian Western sanctions which are hitting its economy. It also is burdened with high inflation and rising unemployment.

The latest rate given by Mesghal extended a loss of nine percent seen immediately as trading opened on Monday, compared with Sunday's close of 29,600.

Some other websites that usually give real-time exchange data, such as Mazanex.com, had the dollar rate for the rial censored.

AFP contributed to this report