Royal Dutch Shell Plc said Wednesday it has stopped selling gasoline to Iran, the latest company to cease business with a country that is increasingly targeted by U.S.-encouraged sanctions.

"We do not currently sell any gasoline to Iran," said Rayiner Winzenried, a Shell spokesman in The Hague.

He declined to say when the sales to Tehran were halted or to relate the move to the call for tighter sanctions.

Reports say the Dutch-Swiss traders Vitol Holding BV and Trafigura also have halted sales to Iran, as has Glencore International AG, another Swiss-based commodities trader.

The United States and its Western allies have been pushing for another round of U.N. sanctions to punish Iran for its refusal to freeze its uranium enrichment program.

Iran also angered the West when it delayed revelations that it was building a secret fortified plant as part of its nuclear program, which Tehran says is designed for peaceful purposes.