The evacuations at the heart of the Middle East's financial hub come as the Gulf but especially the UAE has borne the brunt of Iran's attacks in response to US-Israeli strikes.

Iran's military threatened on Wednesday to attack US and Israeli economic targets in the region, including banks, after overnight attacks reportedly hit an Iranian bank.

Employees were asked to evacuate Citi offices in the Dubai International Financial Centre (DIFC) and in Oud Metha, a source with knowledge of the evacuations told AFP.

British consulting group PwC will close offices in Saudi Arabia, Qatar, the UAE and Kuwait for the remainder of the week as a "precaution", a second source with knowledge told AFP.

Deloitte, another British consultancy, told its staff to vacate their DIFC offices on Wednesday afternoon, a third source with knowledge told AFP.

Employees at two other companies in DIFC told AFP their offices had been evacuated as a precaution.

They all spoke on condition of anonymity given the sensitivity of the matter.

Iran's central operational command, Khatam Al-Anbiya, said "the enemy has given us free rein to target economic centres and banks belonging to the United States and the Zionist regime".

It urged people across the region to refrain from going within one kilometre (half a mile) of banks.

Tehran has targeted US assets in the Gulf but also civilian infrastructure including airports, ports, hotels and landmarks.

- Air, maritime traffic targeted -

Earlier on Wednesday, drones fell near Dubai airport, injuring four people, while attacks hit three ships in or near the Strait of Hormuz.

Iran has targeted Gulf energy infrastructure and choked shipping in the strait -- which normally carries nearly 20 percent of global oil production -- prompting wild swings in prices.

"Two drones fell in the vicinity of Dubai International Airport a short while ago, resulting in minor injuries to two Ghanaian nationals and one Bangladeshi national, and moderate injuries to one Indian national," the Dubai Media Office said.

"Air traffic is operating as normal."

UAE presidential advisor Anwar Gargash said Iran "is lying when they claim to be targeting US bases in the Gulf" and slammed the attacks on "civilian infrastructure... with no regard for civilians and innocent people".

An Indian worker at a cargo terminal opposite Terminal 2 of Dubai airport said he saw a drone flying at low altitude, slowly gliding down before crashing into a building at the airport terminal.

"I saw it clearly. But there was no loud blast when it hit," he said on condition of anonymity.

"About 10 minutes later, I saw another drone gliding past in a similar manner... When it crashed, the explosion was loud."

A container ship and a bulk carrier were hit off the coast of the UAE, one off Dubai and the other off the northern Emirate of Ras Al Khaimah by unknown projectiles, according to the United Kingdom Maritime Trade Operations (UKMTO).

A projectile hit a third ship off Oman, in the Strait of Hormuz, which caused a fire that was later extinguished, the UKMTO said.

And drones struck fuel tanks at Oman's Salalah port on Wednesday, state media said, with private maritime security company Vanguard Tech reporting the suspension of the port's operations after the attack.

Saudi Arabia said it intercepted seven ballistic missiles targeting its eastern region and the Prince Sultan Air Base.

In the past few days, Saudi Aramco's sprawling Ras Tanura facility, home to one of the Middle East's largest refineries, was targeted as well as the UAE's Ruwais refinery -- one of the largest in the world.

str-aya/amj

Saudi Aramco