By Federico Maccioni, Eman Abouhassira and Timour Azhari
DUBAI/RIYADH, Sept 24 (Reuters) - Iranian airlines were barred from neighbouring countries including the UAE and Oman on Thursday in response to new US sanctions, the first big impact of a shift in US policy to target companies in third countries that do business with Iran.
The General Civil Aviation Authority of the United Arab Emirates, the Middle East's biggest travel hub, said that as a result of the new US policy it was suspending all flights
by Iranian airlines until further notice.
Iran's Tasnim news agency reported that flights had also been shut down to Oman, Georgia and Azerbaijan, and to the Iraqi capital Baghdad. It said authorities were working to route flights to another Iraqi airport, in Najaf, a major Shi'ite Muslim religious pilgrimage site.
Washington had announced it would put sanctions on any global companies doing business with Iranian airlines after September 23, with the aim of grounding Iran's entire civil fleet worldwide.
Other countries in the Gulf region also appeared to have restricted flights.
Tehran's Imam Khomeini Airport listed scheduled arrivals and departures on Thursday to and from countries including Afghanistan, Armenia, China, Iraq, Pakistan, Tajikistan and Turkey. But no flights appeared to be listed to or from the nearby Gulf states, with which Iran has long had some of its most important business and travel ties.
Iran has suggested that enforcement of a US-mandated air blockade would lead to potential escalation. On Wednesday, a senior Iranian official threatened to make airports "unusable" in any regional country that abides by the US ban.
Separately on Thursday, authorities in Saudi Arabia said they had intercepted intercepted six ballistic missiles fired by Yemen's Houthi fighters. The Houthis said they had fired dozens of missiles and drones at Saudi targets. An escalating conflict between Saudi Arabia and the Houthis has emerged this month as the combat zone in the wider Middle East war.
'ECONOMIC D-DAY'
With the US-Israeli war against Iran largely stalemated for months on the battlefield, Washington has announced a shift in tactics to extend the reach of its financial sanctions by targeting companies from third countries that do business with Iranian firms, a practice known as "secondary sanctions".
Trump referred to the new strategy last month as "economic D-Day", comparing it to the assault on Nazi-controlled France in World War Two by the United States and its allies.
A flight ban, if sustained, could deepen Iran's isolation and worsen an economic crisis in the country, which is already facing a US blockade of its ports at sea.
"We are living in an open-air prison," a retired teacher in Tehran told Reuters by text message on condition her name not be used.
SAUDI ARABIA SAYS IT SHOOTS DOWN HOUTHI MISSILES
The war, which Trump launched alongside Israel in February as "Operation Epic Fury", has disrupted global energy supplies, killed thousands of people and pushed up oil prices.
Conflicts have been reignited in other regional countries where Iran has allies, initially in Lebanon and now in Yemen, where the Houthis declared a blockade on Saudi Arabia in July and launched a lightning advance this month against a Saudi-backed government.
The Houthis have repeatedly fired into Saudi Arabia this month, and say the Saudi air force has conducted hundreds of strikes on Yemen since fighting escalated.
Saudi Arabia said it had intercepted six Houthi ballistic missiles on Thursday, after issuing emergency alerts for areas including the holy city of Mecca, Jeddah and Yanbu, the main Saudi Red Sea oil port.
"Any escalation and violations by the terrorist Houthi militia will be dealt with firmly," a Saudi-led coalition fighting the Houthis in Yemen said in a statement.
Houthi military spokesman Yahya Saree said the group had attacked Saudi military sites in Jazan province bordering Yemen, targeting operations rooms, command and control centres, weapons depots, missile launch sites and military camps.
Sources in the internationally recognised, Saudi-backed Yemeni government said their forces had repelled overnight Houthi attacks on a key supply route to Aden, the Indian Ocean port city where the government is based.
The Houthis, who already controlled the north including the capital Sanaa, seized Yemen's entire Red Sea coast this month and have been pushing into adjacent highlands near the central mountain city of Taiz and the road from Aden.
The Houthis have kept up pressure on government forces holding a steep winding mountain pass known as Hejat al-Abd, a lifeline for hemmed in pro-government forces, and for goods entering Taiz.
Seizing parts of the Taiz-Aden road could allow the Houthis to tighten their grip around Taiz and deal another blow to the government, which has struggled to regain the initiative since losing the western coast.
More than 700 people have been killed and thousands wounded in the latest fighting, according to the United Nations. Nearly 130,000 Yemenis have been displaced within the country, while more than 3,000 have fled by boat across the Red Sea to Africa.
(Reporting by Eman Abouhassira and Federico Maccioni in Dubai, Timour Azahari in Riyadh and Reuters bureauxWriting by Peter GraffEditing by Timothy Heritage)
