Months after the US killed a top Iranian general in Baghdad, it has offered millions for any details on the mysterious man filling his boots -- Hizbullah power-broker Muhammad Kawtharani.

Washington charged last week that Kawtharani had "taken over some of the political co-ordination of Iran-aligned paramilitary groups" formerly organised by Islamic Revolutionary Guard Corps' Quds Force commander Qassem Soleimani.

In fact, when a US drone strike in January killed Soleimani and others in a small convoy outside the Baghdad airport, the little-known but powerful official from Lebanon's Iran-backed Hizbullah movement was initially rumoured to have died alongside him.

It was quickly confirmed that Kawtharani, who has long spearheaded Hizbullah's Iraq policy, was not among those killed in the attack.

But rumours of his demise only proved his place among the shadowy pro-Iran brokers steering politics in Iraq.

Keen to curb Iran's influence in Iraq, the US last week announced the reward of up to $10 million for any details on Kawtharani's activities or associates.

The State Department accused him of inheriting part of Soleimani's role co-ordinating among pro-Tehran factions that have attacked foreign diplomatic missions and "engaged in wide-spread organised criminal activity".

'The conductor'

Washington had first sanctioned Kawtharani as a "terrorist" in 2013 for providing "training, funding, political, and logistical support" to Iraqi Shia groups.

Born in Iraq in the late 1950s, Kawtharani studied in the holy shrine city of Najaf and is married to an Iraqi woman with whom he has four children.

"Kawtharani was appointed to head Hizbullah's Iraq file in 2003 and has reported directly to its secretary general, Hassan Nasrallah," said a source close to Hizbullah's senior ranks.

In that role, the slender sheikh travelled frequently between Baghdad and Beirut to negotiate with Iraqi figures, particularly during politically turbulent times like government formation and elections.

"In that role, he was like a copy of Soleimani," a senior Iraqi official who met with him several times told AFP.

"He has got a lot of experience and is the only foreigner, after Soleimani, to know the Iraqi political scene inside out," another Hizbullah source said.

Iraqi political expert Hisham al-Hashemi said Kawtharani wore multiple "hats".

"He's the conductor in the Shia loyalist orchestra," said Hashemi, referring to the collection of Iraqi Shia parties that see Iran's Supreme Leader Ali Khamenei as their main reference.

As such, he painstakingly builds consensus among Iraq's varying Shia political and armed factions -- but he has also worked on bringing Iraq's Sunnis on board with their traditional Shia rivals.

A growing profile

Following the US strike that killed Soleimani and top Iraqi commander Abu Mahdi al-Muhandis, Kawtharani saw his portfolio balloon further to include co-ordination with Kurdish parties.

"He became responsible for all the political factions," said Hashemi.

At the same time, he crafted ties between Iraq and Lebanon, where Hizbullah has strained under financial pressure from US sanctions.

"Kawtharani held sway over Iraqi politicians -- so much so that he asked for millions of dollars from Iraq last year to solve Lebanon's financial crisis," a diplomatic source told AFP.

The request was made outside the formal state-to-state channels and it was unclear if it was ever processed.

And while a second Iraqi official confirmed Kawtharani made the request, a source close to the sheikh in Beirut denied the overture.