TEHRAN (AFP) — Iran on Tuesday said it was drafting a parallel budget for next year, which would come into force in the event of an "extraordinary incident" affecting its heavily oil-dependent economy.

The so-called "shadow budget" assumes an oil price of less than 30 dollars a barrel, compared with 33.7 dollars in the actual budget proposed by President Mahmud Ahmadinejad in January for the new year starting March 21.

"We are preparing a shadow budget based on the oil price of under 30 dollars per barrel in case an extraordinary incident happens on the international arena," the deputy head of state-run Management and Planning Organization (MPO), Ali Askari, told reporters.

He did not specify what such an incident might involve.

Falling global crude prices are a major concern for Iran at time when the UN Security Council has imposed sanctions on Tehran for its refusal to suspend nuclear activities.

The sanctions are targeted not to affect the wider economy but the United States has threatened to tighten up the penalties if Iran does not comply. It is also pressuring European banks to limit their dealings with Tehran.

Although Washington emphasizes the standoff should preferably be solved through diplomacy, it has also never ruled out military action to thwart Iran's nuclear program.

Ahmadinejad has promised to use only oil export income from a 33.7 dollars per barrel oil price for the annual budget, with any surplus revenue saved in a fund to back the economy in case of oil price fluctuations.

Even with that low base price, MPs and analysts believe such accounting only works on paper and fear that the government will inevitably use more oil revenues for current expenditure.

Iran's economy is heavily dependent on oil revenues, which account for 80 percent of total export earnings and cover more than 50 percent of the state budget.