President Bush says he will seek stronger sanctions on Iran, following a new U.N. report that accuses Tehran of accelerating its nuclear-enrichment program. VOA's Paula Wolfson has details from the White House.

The president makes clear Iran's defiance of international demands will not be tolerated.

"My view is that we need to strengthen our sanctions regime," he said.

Mr. Bush says Secretary of State Condoleezza Rice will begin negotiations with other nations on an expanded U.N. sanctions regime. And he says he will get personally involved in talks on the matter with Russia and China.

"The first thing that these leaders have got to understand is that an Iran with a nuclear weapon would be incredibly destabilizing for the world," he said. " It is in their interest that we continue to work collaboratively to isolate that regime."

An International Atomic Energy Agency report issued Wednesday said Iran has neither stopped enriching uranium, as demanded by the Security Council, nor has it opened its nuclear facilities to the extent sought by monitors.

The IAEA says that lack of transparency is compromising its ability to track the Iranian nuclear program, which Tehran says is designed for peaceful purposes.

The United States and its allies have said monitoring is crucial because the type of nuclear technology sought by Iran can also be used to create nuclear weapons. The IAEA chief has said Iran may be able to produce weapons in as few as three years.

The nuclear issue is just one of the factors causing increased tensions between the United States and Iran. Washington recently moved two aircraft carriers and seven ships into the Persian Gulf for military maneuvers. And Iran is detaining several American citizens, including a leading Iranian-American scholar who works for a Washington-based foreign policy research organization.

At a White House news conference, President Bush said Washington has made its concerns known to Tehran.

"We have made it very clear to the Iranian government that the detention of good decent American souls who are there to be beneficial citizens is not acceptable behavior," he said.

The United States and Iran are expected to hold talks Monday in Baghdad on the security situation in Iraq. The White House says those talks will not include the nuclear issue or Iran's detention of American citizens.