President Bush says Iran should face international sanctions, if it ignores a United Nations deadline for halting nuclear enrichment activities. Mr. Bush spoke after Iran's supreme leader pledged to continue pursuing nuclear technology.

President Bush says defiance of U.N. Security Council mandates must not be tolerated. At a White House news conference, Mr. Bush was asked if he believes the Security Council will promptly take action to punish Iran, if Tehran fails to comply with an August 31 deadline to stop enriching uranium, material that could be used to build a nuclear weapon.

The president's reply: "I certainly hope so."

President Bush speaks during news conference  Monday, Aug. 21, 2006

"In order for the U.N. to be effective, there must be consequences, if people thumb their nose at [defy] the United Nations Security Council. And, we will work with people in the Security Council to achieve that objective," the president said.

Earlier, Iranian Supreme Leader Ayatollah Ali Khamenei suggested there would be no halt in the country's pursuit of nuclear technology.

State-run television quoted the ayatollah as saying that Iran has made its decision on nuclear matters and, with patience and power, will continue on its path. He described the United States as one of several "arrogant powers" pressuring Iran, under what he said is the false belief that Tehran is pursuing nuclear weapons.

Iran has long insisted its nuclear program is for purely peaceful purposes, to generate energy for a growing population.

President Bush said he wants the dispute with Iran to be resolved diplomatically, but said, for that to happen, the international community must speak to Tehran with one voice.

He added that U.S. concerns over Iran extend beyond its nuclear program, and include its sponsoring of international terrorism.

"Iran is obviously part of the problem. They sponsor Hezbollah. They encourage a radical brand of Islam. Imagine how difficult this issue would be, if Iran had a nuclear weapon," the president said. "And, therefore, it is up to the international community, including the United States, to work in concert for effective diplomacy."

The ayatollah's statement could foreshadow Iran's formal response to an international package of incentives to halt uranium enrichment. Tehran has pledged to give its answer by Tuesday.