A top Iranian airline official says Iranian planes have been refused fuel at airports in other countries, since the United States implemented new sanctions against Iran last week.
The Iranian news agency ISNA quoted Mehdi Aliyari as saying airports in Britain, Germany and the United Arab Emirates have refused fuel for Iranian planes.
Officials in Britain, Germany and the UAE denied knowledge of a ban on refueling Iranian planes. But a source in the UAE said a private firm had refused to refuel an Iranian plane there.
Meanwhile, Iran is dismissing the economic impact of the new U.S. sanctions, which target Iran's energy and banking sectors.
President Mahmoud Ahmadinejad said Monday that Iran's people will prove the sanctions to be a failure. Oil Minister Massoud Mir-Kazemi said the sanctions are "nothing new" and would not affect Iran's energy sector.
The U.S. sanctions aim to make it harder for Iran's government to buy refined petroleum and exclude from U.S. markets companies involved in selling gasoline, jet fuel and other such products to Iran.
Western financial newspapers have reported that British oil giant BP is refusing to refuel Iranian airlines. BP officials refused to comment on individual contracts with airlines, but said the company will comply with international sanctions in countries where it operates.
BP leased the oil drilling rig that exploded in the Gulf of Mexico in April, killing 11 workers and causing a massive oil release that continues to this day.
Mr. Obama said the new U.S. sanctions will strike "at the heart" of Iran's ability to fund and develop its alleged nuclear weapons program.
Iran says its nuclear program is peaceful, but Western nations suspect Iran is trying to build atomic weapons.
Some information for this report was provided by AFP and Reuters.