Factbox: U.S. sanctions firms with links to Iran

(Reuters) - The United States on Thursday imposed sanctions on Chinese state-run energy trader Zhuhai Zhenrong Corp, which it said was Iran's largest supplier of refined petroleum products, as it sought to impress on Beijing and Tehran its resolve to increase economic pressure over Iran's nuclear program.

Washington also imposed sanctions on Singapore's Kuo Oil Pte Ltd and United Arab Emirates-based FAL Oil Company Ltd.

Here are some details about the three companies:

ZHUHAI ZHENRONG

Zhuhai Zhenrong Corp is one of China's top four state petroleum traders, along with Unipec and Chinaoil -- the trading departments of Sinopec Corp and PetroChina respectively -- and Sinochem Corp.

The company was established in 1994 as the exclusive Iranian crude oil importer, supplying the oil mainly to refineries owned by top refiner Sinopec Corp and a small part to PetroChina.

For the last decade, Zhuhai Zhenrong has maintained its crude import volume from Iran through annual supply pacts at about 240,000 barrels per day (bpd), or roughly 5 percent of total crude imports into China.

The firm was until the late 1990s affiliated to China's national defense industry, before becoming a state-run commercial firm directly under the supervision of the State-owned Assets Supervision and Administration Commission (SASSAC).

Its refined fuel business has largely been handled by subsidiary Guangdong Zhenrong Energy Co. Ltd, an oil and commodity trader that was fully owned by Zhuhai Zhenrong until 2011.

New management took over Zhuhai Zhenrong in 2010, seeking to grow its business beyond the dominant Iranian oil procurement. It is looking at upstream oil and gas development and other investment opportunities.

FAL OIL

Middle East-based FAL Oil is one of the largest independent oil and bunker traders in the Gulf, with total sales for 2009 at 20 million tonnes of fuel oil, gas oil and various petroleum products, according to the company website.

FAL sources its cargoes from the international market, and had been one of the main buyers of Iranian fuel oil until last year. It is a major supplier of oil to the Red Sea, the Mediterranean, the Indian Subcontinent, East Africa and occasionally to some regions in the Far East.

The company opened its office in the UAE emirate of Sharjah in 1969. It also operates offices in Singapore and Britain.

FAL Oil trading has scaled back trading operations in the past 18 months due to credit issues.

In October, Pakistan State Oil blacklisted the company from participating in its tenders after FAL failed to meet its contractual agreements.

KUO OIL

Singapore-based Kuo Oil is one of Asia's major fuel oil traders, and has regularly bought the product from Iran since last year, after a three-year hiatus.

The firm, which has been a major presence in the fuel oil market for nearly 20 years, also owns and operates an oil terminal with a capacity of 1.0-1.5 million cubic meters, Tankstore Terminals, at the city-state, which it shares with oil major BP.

It trades mainly in the region, buying the product from other players and selling into Singapore's bunker market, the world's largest, and to regional consumers such as Vietnam and Indonesia.

The company was founded by Malaysian Peter Fu Yun Siak, and is now run by his son, Peter Fu Chong Cheng.