Royal Dutch Shell and Italian refiners are maintaining crude oil trade with Iran at a time when other oil majors and big refiners are halting orders amid UN-imposed sanctions, traders said on Tuesday.

A Shell spokesman said the company was complying with all legislation.

The United Nations imposed sanctions in June in reaction to Iran's uranium enrichment programme and although the sanctions excluded Iranian oil exports it has made trade financing very difficult and deterred many firms with large U.S. operations.

Among major oil companies, BP has trimmed its exposure to Iranian crude and last week industry sources said Portuguese oil company Galp had scaled back its purchases.

US refiners have long been prohibited from processing Iranian crude under sanctions, but refiners elsewhere face no such ban. Asia is the top market for Iran, with China and India thought to be destinations for large amounts.

Traders said finding the right banks to agree to pre-finance deals was the key challenge to doing business with Iran and so far only Shell and some Italian refiners have remained large customers in Europe.

'Banks are completely shut. There is very little going from Iran. Shell has some financing from Chinese banks and Italian refiners are getting some volumes with the help of Italian banks,' one major player on the Mediterranean crude market said.

'We do not comment on our trading activities but would underline that we continue to comply with all legislation. As you know, it is not illegal to lift oil from Iran,' a Shell spokesman said.

'It is untrue to claim we purchase crude oil at a discount. We buy at the Official Selling Price that each producer makes public to buyers,' he added.

Another trader said the market was aware that Italian firms Agip and Saras were importing Iranian crude with the financing help from Italian banks. Agip and Saras were not immediately available for comments.

'(Italian refiner) ERG could have the opening of banks in the near future,' the first trader said.

The comments from traders follow a report by Britain's Guardian newspaper on Tuesday which cited sensitive trading documents as saying Shell has bought $1.5 billion worth of crude oil from the National Iranian Oil Company (NOIC) this summer.

Industry sources told Reuters Shell was lifting 80,000 barrels per day of Iranian crude under a term contract, which would be worth only around $500 million in June-August.

'Trade continues and will continue until things change politically. Business is pretty much where it has been,' said a Shell insider.

Wide-ranging international sanctions implemented in June and July have excluded crude oil sales, but Western-allied powers have increased political pressure on countries to trade less with Iran. – Reuters