* Oil buyers rush to book alternative supertankers
* VLCC loading Mideast oil for N. Asia in Oct costs $600,000 more
* India's Reliance books 2 VLCCs at much higher rates
* COSCO owns biggest oil tanker fleet in the world
* 2 COSCO VLCCs meant to load U.S. Gulf crude for Asia dropped (Adds higher VLCC rates for India; arrangements for COSCO ships to load U.S. oil for Asia cancelled)
SINGAPORE, Sept 27 (Reuters) - Key oil freight rates from the Middle East to Asia rocketed as much as 28% on Friday in a global oil shipping market spooked by United States sanctions on units of Chinese giant COSCO for alleged involvement in ferrying crude out of Iran.
In what the State Department called "one of the largest sanctions actions the U.S. has taken" since curbs were re-imposed on Iran in November last year, two units of COSCO were named alongside other companies in claims of involvement in sanctions-busting shipments of Iranian oil. 1/8
The surprise move, affecting one of the world's largest energy shippers, operating more than 50 supertankers, comes as President Donald Trump seeks to exert maximum pressure on Iran to drop nuclear programmes.
As some Asian oil buyers rushed to the shipping market to secure vessels, rates for chartering supertankers, or Very Large Crude Carriers (VLCCs), to load crude oil from the Middle East to north Asia in October surged nearly 19% overnight to about 75-76 points on Worldscale, an industry tool used to calculate freight charges, shipping and industry sources said.
That means an increase of about $600,000 for each ship, a Singapore-based crude oil trader said.
The rates for loading Middle East crude to west coast India in the second week of October jumped 28% to 80-92.5 points after Reliance Industries Ltd booked two supertankers overnight, industry sources said.
But there was also uncertainty over how widely the sanctions on the COSCO units - COSCO Shipping Tanker (Dalian) Co, Ltd and its subsidiary COSCO Shipping Tanker (Dalian) Seaman & Ship Management Co, Ltd - will be implemented. Industry sources said some oil buyers were holding off hiring COSCO tankers while they check with legal teams to better understand the impact of the sanctions.
"The market is fearful of sanctions so refiners are taking some preventive measures. We'll have to see how widely implemented the sanctions will be," said KY Lin, spokesman for Taiwanese refiner Formosa Petrochemical, a major crude oil buyer in Asia.
Friday's jolt left shipping rates springing back to levels not seen since mid-September drone and missile strikes on key Saudi Arabian oil production facilities roiled global markets. The COSCO vessels are equal to about 7.5% of the world's fleet of supertankers, according to Refinitiv data.
"Charterers are in trouble," a North Asian shipbroker said, declining to be named citing company policy. "It was terrible news for every one of us with the Saudi drone attack, and now the market has to deal with U.S. sanctions on COSCO."
"Good news for owners, good time for them to earn money," the broker said.
While diplomatic tensions between the United States and Iran remain high, a British-flagged tanker that had been detained by Iran in the Strait of Hormuz on Friday left Bandar Abbas port heading for international waters.
On Thursday, Unipec, the trading arm of Asia's largest refiner Sinopec and India's largest refiner Indian Oil Corp, cancelled bookings of some COSCO ships and scrambled to find alternative ships to move their crude on. 1/8
"Rates have definitely been pushed higher by these sanctions," said an executive at a top shipbroker in Singapore, adding that ships carrying Middle East and U.S. crude to Asia were subject to the biggest impact. The broker declined to be identified, citing company policy.
Crude shipments from the United States to Asia have also been affected. Industry sources said provisional bookings for VLCCs Cosmerry Lake and Yuan Qiu Hu to load U.S. oil in the second half of October had been scrapped. Cosmerry Lake is owned by Cosmerry Lake Maritime Inc and managed by Cosco Shipping Tanker (Dalian), while Yuan Qiu Hu is owned and managed by Cosco Shipping Tanker (Dalian).
COSCO officials were tight-lipped on Friday.
"(The) company is assessing the situation and impact internally as soon as possible, but so far we don't have anything to update you," said Zhang Zheng, an investor relations official with COSCO Shipping Energy Transportation, parent of COSCO Shipping Tanker (Dalian) Co, Ltd.
Trading in shares of COSCO Shipping Energy Transportation was halted on Thursday after the news on the sanctions, and will remain halted on Friday.
(Reporting by Florence Tan, Chen Aizhu and Roslan Khasawneh Writing by Gavin Maguire Editing by Kenneth Maxwell)