U.S. and European sanctions meant to block Iranian crude oil deliveries went into force this summer. The sanctions are meant to encourage Iran to be more forthcoming about its nuclear program, which Tehran maintains is for peaceful purposes.
Some governments like Japan received a sanctions waiver from the U.S. government for "significantly" cutting back on Iranian crude oil imports.
None of Iran's oil was delivered to Japan in July in part because of European sanctions targeting shipping insurance.
"We are optimistic about securing an extension (from Washington), judging from the state of negotiations," a Japanese government source told the Platts news service.
Platts in June forecast that Japan's crude and fuel oil demand for power generation was expected to be around 700,000 barrels per day from July through September because of a nuclear power shortage in the country. A continuation of the reduction of imports from Iran would be needed for a waiver extension.
The current 180-day period expires Saturday.