UPDATE 1-Asia's Iran oil imports fall 11.5 pct in Jan-Sept
* Asia's Jan-Sept Iran oil imports fall to 953,567 bpd
* Asian buyers Iran Sept imports jump 30 pct to 1.2 mln bpd
* Waiver reviews on U.S. sanctions due Nov-Dec
TOKYO, Oct 31 (Reuters) - Iran's top four crude buyers cut their purchases by 11.5 percent in the first nine months of the year, with oil shipments set to remain under pressure from sanctions despite tentative signs of better relations between Tehran and Washington.
Western sanctions have forced China, India, Japan and South Korea to reduce their reliance on Iranian oil, more than halving the OPEC nation's exports since early 2012 and costing it billions of dollars a month in lost revenue.
The four major Asian buyers between January and September imported 953,567 barrels per day (bpd) of Iranian crude, down 11.5 percent from the same nine months in 2012, according to government statistics and oil tanker arrival schedules.
In the month of September, they imported 1,161,304 bpd of Iranian oil, a 30.2 percent jump from a year ago.
The European Union and the United States believe Iran is developing nuclear weapons, while Iran says its programme is for power generation.
Since the beginning of 2012, U.S. and European sanctions have cut Iran's oil exports in half to about 1 million bpd.
Iran and six big powers began expert-level talks on Wednesday, building on diplomatic momentum created by a pragmatic shift in Tehran towards negotiating a peaceful solution to the dispute over Iranian nuclear ambitions.
However, despite much friendlier contacts between the sides since Hassan Rouhani took office as Iranian president with a pledge to reduce tension with the West, major differences remain to be overcome for any breakthrough deal to be reached.
Top White House administration officials have been pushing U.S. lawmakers to hold off on new sanctions over Iran's nuclear programme, but some key lawmakers said on Wednesday they had not been convinced to support a delay in putting in place new measure aimed at Tehran. (Reporting by Osamu Tsukimori and James Topham; Editing by Tom Hogue)