Iran is losing half of its oil revenues because of international sanctions imposed over its disputed nuclear programme, Economy Minister Shamseddin Hosseini said in remarks quoted by media on Monday.

"Iran is facing a 50-percent drop in its oil revenues due to sanctions," Hosseini told state television, Jomhuri Eslami newspaper reported.

Hosseini put down the loss to difficulties in repatriating oil money.

Subject to harsh Western sanctions over its controversial nuclear work, Iran is struggling against what it calls an "economic war" to cope with punitive measures targeting its vital oil income and access to global financial systems.

An oil embargo on Iran imposed by the European Union came into effect in July, ending European purchases of Iranian crude and also decreasing Tehran's oil exports to its Asian customers from 10 to 30 percent.

According to the International Energy Agency, Iranian exports in November were estimated at 1.3 million barrels per day, down from nearly 2.3 million last year.

A number of Iranian lawmakers and government officials have hinted that the drop in oil revenues will shrink the budget for the next Iranian calendar year, starting on March 21, 2013.

In early September, President Mahmoud Ahmadinejad acknowledged that Iran had "some problems" in selling its oil because of the sanctions.

Iran insists its programme of uranium enrichment is for purely peaceful purposes, and denies Western and Israeli allegations that it wants to manufacture nuclear weapons.