Rome  - UN Secretary-General Ban Ki-moon was expected to urge world leaders attending a summit in Rome Tuesday to lift trade restrictions, taxes and other price controls that have helped spur food prices to their highest levels in 30 years.

Ban was set to address delegates from some 50 countries at the UN Conference on World Food Security's inaugural ceremony scheduled to begin at 0700 GMT.

The three-day summit, hosted by the UN's Food and Agriculture Organization (FAO), is aimed at winning donor pledges for urgent aid to help millions of people facing hunger because of soaring prices.

FAO has listed 22 countries that are particularly vulnerable due to a combination of high levels of chronic hunger - defined as more than 30 per cent undernourishment - and being net importers of both food and fuel. Countries such as Eritrea, Niger, Comoros, Haiti and Liberia are particularly affected.

The summit's first goal is to win from donors an emergency aid package, including direct food distribution, food subsidies and cash transfers, as well as feeding programmes for schoolchildren, pregnant women and the elderly.

Those emergency measures would require 775 million dollars, according to a donor appeal issued by another Rome-based UN agency, the World Food Programme.

FAO also mentioned short-term measures such as the distribution of seeds, fertilizers, animal feed and other inputs small-scale farmers through vouchers or other forms of subsidies. It said 1.7 billion dollars in donor aid would be required.

The UN is also expected to try to persuade the United States and other nations to consider phasing out subsidies for food-based biofuels that currently act as incentives for farmers to switch their production away from food.

However, some of the summit's proceedings risk being overshadowed by controversy around the attendance of Iranian President Mahmoud Ahmadinejad and Zimbabwe's President Robert Mugabe.

Ahmadinejad, speaking on the eve of his departure for Rome, lashed out against the US, saying its "satanic power" faced destruction and reiterated his threats that Israel would be wiped off the world map.

On Tuesday, the Iranian president was scheduled to hold a news conference at FAO's Rome headquarters at 1400 GMT. Jewish groups and other critics condemned his attendance.

Mugabe, who is in Rome with his wife Grace, has been allowed to circumvent a European Union travel ban on him and about 200 members of his ruling elite, because of a loophole that permits them to attend UN meetings.

Britain and Australia have described Mugabe's presence in Rome as "obscene." (dpa)