Iran's president on Monday described U.S. sanctions imposed on Iran as an economic war being waged on his country and stressed that "economic war is more difficult than military war."

Hassan Rouhani spoke as he inaugurated the third and final phase of the sprawling Persian Gulf Star refinery built in the Persian Gulf port city of Bandar Abbas. Construction of the refinery began in 2006 and it now has the capacity of 400,000 barrels a day, which amounts to about 20 percent of Iran's 2.1 million barrels of daily refining capacity.

Rouhani praised the inauguration, saying in a televised speech that it comes despite America's "imposing the harshest sanctions" on Iran.

The Trump administration last year pulled the U.S out of Iran's nuclear deal with world powers and re-imposed sanction on Iran, targeting its vital oil sector.

"We have inaugurated huge national projects in this situation," Rouhani said at they inauguration, adding that this comes despite efforts by the U.S., Israel and their allies to increase pressures on Iran.

Also Monday, spokesman for Iran's Foreign Ministry dismissed U.S. reports of a former U.S. Air Force counterintelligence specialist who defected to Iran despite warnings from the FBI. Monica Elfriede Witt, 39, has been charged with revealing classified information to the Tehran government, including the code name and secret mission of a Pentagon program.

"I think it is not true, and that it is media propaganda aimed at Iran," said Bahram Ghasemi, he spokesman, without going into specifics.