Iraq's Kurds would face enormous challenges if they were to secede, but the threat of an independence vote amid chaos nationwide could squeeze concessions from the federal government, experts say.

Their autonomous three-province northern region expanded its control over a swathe of territory that Baghdad also claims when Kurdish peshmerga fighters moved in last month to areas from which Iraqi soldiers withdrew during a sweeping Sunni militant onslaught.

That emboldened Kurdish president Massud Barzani to call for a referendum on independence, which he said would be a "powerful weapon" in Kurdish hands after years of bitter haggling with Baghdad over oil, territory and funds.

But experts say secession soon would be fraught with danger, and that the threat of a vote is more likely a bargaining tool on a longer road to independence.

One of the biggest obstacles to Kurdish secession is money, with oil revenues from areas they control insufficient to pay for the region's numerous civil servants, and future revenues in doubt because of objections from Baghdad, which considers independent Kurdish energy exports to be illegal.

The dispute with the federal government has led Baghdad to withhold the 17 percent share of the national budget allocated to the Kurdish regional government (KRG), and the landlocked region's ability to augment its income relies on exporting oil through the Turkish port of Ceyhan.

- Anathema to Turkey -

"The current financial position of the KRG is very weak, and exporting oil through Ceyhan has been difficult," said Ayham Kamel, Middle East and North Africa director at the Eurasia Group consultancy.

"There is no short-term solution for the Kurds finding an alternative financing structure to what they find in Baghdad."

Kurdish independence has in the past been anathema to Turkey, which also has a sizeable Kurdish minority, but Ankara has since softened its stance.

Whether that lasts beyond August 10 elections, in which Prime Minister Recep Tayyip Erdogan hopes to rally the Kurdish vote, and whether the Kurds are happy to swap dependence on Baghdad for dependence on Ankara, remains to be seen.

While the Kurds struggle for money, they are also financing an expensive campaign to keep a raging Sunni insurgency led by Islamic State (IS) jihadists from their borders and out of disputed areas vacated by the retreating Iraqi army.

But with the IS militant onslaught held in check by state forces further south, experts say it is only a matter of time before they turn their focus on the north, which may force the KRG to call for Baghdad's help.

Meanwhile, Kurdish politicians are fighting for key posts in Iraq's new government after April polls, indicating they are hedging their bets on independence.

- Barzani ploy could backfire -

"This is just a way to put pressure on the Baghdad government, and the proof of that is that they're still battling for the post of president and other posts on the political map," Ihsan al-Shammari, a politics professor at Baghdad University, said of the independence referendum.

Such a ploy could backfire on Barzani, however, given the Kurds' long-time aspirations for a separate state.

"He can wave that sword around his head when he's looking toward Baghdad, but his population (is) deeply committed to independence and has in the past been frustrated he hasn't driven them there," said Toby Dodge, director of the Middle East Centre at the London School of Economics.

"I don't think he can flirt with his population without sowing deep alienation if he doesn't deliver it."

The United States, which the Kurds are keen to cultivate as an ally, has warned against a rush for independence, while Shiite Iran, a powerful neighbour to any future Kurdish state, is unlikely to condone a unilateral breakaway from Shiite-led Iraq.

With Turkish support uncertain, strained finances, insurgents at the door, and the possibility of revolt by Arabs in disputed lands that Kurdistan intends to fold into its realm, experts do not expect the birth of a new nation soon.

"You'd end up with a dead state," Shammari said.