Oil trade with Iran remains more difficult following tougher sanctions against the Islamic Republic, industry sources said, despite a message from the European Union that such operations are legal.

Saras, an Italian oil refiner, said last week that transactions with Iran have become more challenging as banks are reluctant to get involved.

Other European oil companies have made similar remarks privately.

'The banking side is the tough part. It is very tough. It has to be banks that haven't got any kind of interests in the United States,' said an Iranian crude oil customer in Europe.

Iran is a major oil exporter and its production is equal to about 4.2 per cent of daily world demand. The amount of Iranian crude sold to countries that are members of the International Energy Agency declined by 22 per cent in August.

The financing hurdle follows a host of sanctions on Iran over its nuclear work passed this year by the United Nations, European Union and the United States.-Reuters