"We hope the fighting will stop tomorrow, as every day of delay has negative repercussions on the global economy," UN assistant secretary-general Abdallah Al Dardari told reporters in Amman.

"We estimate that the loss to the Arab region's GDP as a result of one month of fighting will be around six per cent... Six per cent of GDP means the region has lost around $186 billion from its economy in a single month," he said.

Al Dardari, who is also a top UN official for the Arab region, said the countries of the oil-rich Gulf were shouldering the heaviest burden.

"The impact on GDP is very significant in the Gulf region, where it could reach $168 billion, and in the Levant region, where it could reach around $30 billion," he said.

The war that erupted with a US-Israeli attack on Iran on February 28 spread quickly across the region, as Iran launched retaliatory attacks targeting Gulf countries and Israel.

Lebanon and Iraq have been drawn into the fighting, with pro-Iran groups launching attacks of their own on Israel and US interests.

Al Dardari warned against the Gulf's economic dependence on oil, saying the crisis around the vital waterway of the Strait of Hormuz had proved the need to diversify.

He also said there was a need to seek out routes other than the Strait of Hormuz, through which a fifth of global oil and liquefied natural gas flowed pre-war.

"The Arab economy relies on virtually a single commodity; even countries that do not export oil depend on remittances from expatriates in oil-exporting countries and on aid from those same countries, while the oil-exporting countries themselves rely on a single product," he said.

"This fragility in the Arab economy is demonstrated by recent events, which prove that it is unsustainable."

Dardari sounded the alarm over the expected impact on jobs in a region already wracked by inequality.

"We estimate that the number of jobs we will lose as a result of this conflict is around 3.7 million," he said.

"As for the impact on poverty, we expect that around four million more people in the region will fall, or have already fallen, below the poverty line this month as a result of the hostilities."