(Adds details, background)

* No oil imports from Iran in Sept, 1st time since Sept. 2012

* Jan-Sept Iran crude imports fall 49.1 pct y/y to 7.15 mln tonnes

* Total Sept crude imports at 10.83 mln tonnes, down 11.8 pct y/y

SEOUL, Oct 15 (Reuters) - South Korea did not imported any oil from Iran in September for the first time in six years, before U.S. sanctions against the Middle East country take effect in November, customs data showed on Monday.

The last time South Korea did not import oil from Iran was September 2012, according to customs data.

South Korean buyers, among major Asian buyers of Iranian oil, suspended Iranian oil loading from July due to the uncertainty of getting a waiver from the U.S. government.

The South Korean government has been in talks with the U.S. government to get exemptions on Iran crude imports. During the previous rounds of sanctions from 2012 to 2015, South Korea could buy Iranian oil by capping its Iranian oil imports volume.

A U.S government official said in early October that the U.S. government was actively considering waivers on sanctions for countries that are lowering their imports of Iranian oil.

Oil imports from Iran have declined for the past months. In the first nine months of the year, South Korea’s imports of Iranian oil dropped 49.1 percent to 7.15 million tonnes, compared with the same period a year earlier, according to the data.

In total, the world’s fifth-largest crude buyer, imported 10.83 million tonnes of crude oil in September, down 11.8 percent from 12.28 million tonnes a year earlier.

Imports from Saudi Arabia, South Korea’s top crude supplier, were 3.41 million tonnes in September, down 6.9 percent from 3.67 million tonnes a year earlier.

Meanwhile, South Korea’s imports of U.S. crude increased five-fold to 668,704 tonnes in September from 131,125 tonnes last year, the data showed.

In the January-September period of the year, 110.45 million tonnes of crude oil, were imported into South Korea, nearly unchanged from 110.44 million tonnes over the same period last year.

State-run Korea National Oil Corp (KNOC) will release South Korea’s final September crude oil imports data later this month. (Reporting By Jane Chung; editing by Emelia Sithole-Matarise)