The centre of the storm is expected to hit land in southeastern Iran, possibly disrupting shipping through the Gulf.
The authorities evacuated hundreds of residents of the Iranian port of Chabahr on the Coast of Oman Sea on Wednesday out of fear of
the approaching cyclone, a local official said.
Iranian state television said that floods, caused by the heavy rainfall, have already cut some major roads in southeastern Iran.
Winds gusting up to 110km per hour have reached costal areas near the Jask town, 1,800km southeast of Tehran, the TV said.
Cyclone Gonu was expected to reach Muscat, Oman's capital, on Wednesday.
Ahmed al-Huti, Al Jazeera's correspondent in Oman, said heavy rain blanketed the city, covering almost all roads.
He said power was cut in some areas in Muscat.
Electricity and phone lines have been cut off in all eastern areas in Oman, al-Huti said. Satellite and land broadcast could not be carried either.
Sources told Al Jazeera that much properties was damaged, particularly in coastal areas, but there were no immediate reports of human casualtlies.
The situation is expected to last for three days, al-Huti said.
Oman's Sur export terminal, which handles 10m tonnes of liquefied natural gas exports every year, would be closed for at least 48 hours, a shipper said. Sultan Qaboos port, which handles vehicles and containers, was also closed.
The Mina al Fahal oil terminal, the only outlet for Oman's 650,000 barrels per day of crude oil production, closed during the day as storms hit the area. Rashid al-Barwani, an oil official, said it had since reopened and delays would be short-lived.
|Strong waves battered the coast of Oman |
as the cyclone approached [EPA]
Production was also suspended at the Mukhaizna oil field, with an estimated output of about 10,000 barrels per day, but it may resume on Wednesday, Nasser bin Khamis al Jashmi, undersecretary at the oil ministry, told state television.
Oil prices surged above $70 on news of the cyclone in the Gulf region, which supplies one fifth of the world's oil.
Saudi Arabia, the world's top oil exporter, said its main oil region would not be affected. Kuwait's oil refining company said everything was operating as normal there.
The weather centre of the neighbouring United Arab Emirates, an Opec oil exporter, said the cyclone was expected to bring rain on Wednesday with clouds emerging over its eastern coast.
"Its full strength will become apparent in the next 24 hours. In 2002, we had a similar storm. They happen in the area from mid-May to the end of June," Salama Hashshad, an official at the central forecasting unit, said.
Oman's state media had earlier said that thousands of people were evacuated from the Masirah Island in the Arabian Sea, but an Omani disaster relief official said that the cyclone had changed direction leaving the island unharmed.
Oman's official television station urged people to stay in their homes or go to buildings that could withstand strong winds, to avoid highways and to turn off electricity. The police are on high alert.
Official media said Oman's stock exchange would close along with all private and public sector institutions until Saturday.