The Islamic Republic is under intense pressure from US and European trade and financial restrictions imposed over its disputed nuclear programme.

The sanctions have led to a sharp drop over the past year in its oil exports, a major source of revenue for Tehran. Iran's state budget for the next fiscal year may assume exports of just 1 million barrels of oil a day, according to a report by the semi-official Fars news agency this week, about half volumes shipped in 2011.

Japan, the world's third-biggest oil consumer, imported 773,542 kilolitres (156,949 barrels per day) of Iranian crude last month, compared with 891,300 kl (186,870 bpd) in October, according to data from the Ministry of Economy, Trade and Industry (METI). (1 kl=6.2898 barrels)