BEIJING/LONDON--China is scouring the world for alternative oil supplies to replace a fall in its imports from Iran, as it seeks to negotiate lower prices from Tehran, and has been drawing heavily on Saudi Arabia.

Industry sources told Reuters that Beijing had bought the bulk of an increase in crude oil supplies from top oil exporter Saudi Arabia in the last few months. The world's second-largest oil consumer is also importing more cargoes from West Africa, Russia and Australia to replace reduced supplies from Iran.

China is the top buyer of Iranian oil, taking around 20 percent of its total exports, but since January it has cut purchases by around 285,000 barrels per day (bpd), or just over half of the total daily amount it imported in 2011.

Saudi Arabian output reached 9.76 million barrels per day (bpd) in December, up 360,000 bpd from October, OPEC data show, and has remained near that level in January, according to a Reuters survey. Several sources in the oil industry said China has bought a good part of the extra oil.

"On average, Saudi exports went up by 200,000 barrels per day and this went to the East, overwhelmingly to China," said one of the sources, a senior executive with the trading arm of a U.S. oil company.

A source familiar with the matter, who declined to be identified by name, also said the kingdom had been supplying about an extra 200,000 bpd to China since November.

Oil traders believe Unipec, the trading arm of China's top refiner Sinopec Corp., has been using a flexibility clause in deals, known as tolerance, to buy more oil under term contracts, especially as Saudi official selling prices in the past two months have been attractive. "Under the current circumstances, it is necessary to use the tolerance to adjust lifting volumes," a Chinese oil trader said. Unipec declined to comment.

Official Chinese data also show an increase in crude oil imports from Saudi Arabia in the last few months, but on a smaller scale than the rise given by the industry sources. China imported 1.12 million bpd of crude from Saudi Arabia in December, customs data show, down from 1.17 million bpd in November. That is still up from October's 1.07 million bpd.