The Bush administration insisted Wednesday that international sanctions against Iran are having some impact despite a new government report questioning their usefulness. Secretary of State Condoleezza Rice goes to Berlin next week seeking a new U.N. sanctions resolution against Tehran because of its nuclear program. VOA's David Gollust reports from the State Department.

Administration officials are defending their policy of seeking escalating sanctions against Iran in the face of a report by government experts that the impact of sanctions is hard to quantify and blunted by Tehran's growing oil income.

An assessment of Iran sanctions by the non-partisan Government Accountability Office or GAO, the investigative arm of Congress, is due for release later this week but its contents have already been leaked to the news media.

According to press accounts, the GAO report says the impact of sanctions aimed at discouraging investment in, and business with Iran, is hard to determine and been counteracted by an avalanche of Iranian oil revenues. The GAO called on the administration to do a baseline assessment of the sanctions' value and report to Congress.

The U.S. Treasury Department, in a response to the GAO report, said Iran is experiencing increased economic isolation because of U.S. and international sanctions, and that the viability of its state-owned banks is threatened.

At a press briefing, State Department Spokesman Sean McCormack acknowledged the difficulty of obtaining accurate economic data from Iran's opaque government. But he said the administration's general assessment is that sanctions have had some effect, and over time could become quite severe:

State Department spokesman Sean McCormack

"It takes a while for sanctions to have their full effect, and we are only doing this now in an incremental manner," said Sean McCormack. "So we have very consciously followed a policy of ratcheting-up the pressure in increments. So you are not going to see, all of a sudden, draconian sanctions put in place that would have a dramatic effect on the Iranian people. Now that said over time, if the Iranian government persists in its current behavior, there are going to be effects on the Iranian people."

The United States has imposed wide-ranging financial sanctions against Iranian banks and prominent individuals for that country's failure to heed U.N. demands that it stop uranium enrichment, and its alleged support for international terrorism.

It has also spearheaded successful efforts in the U.N. Security Council for two nuclear-related sanctions resolutions. However a drive for a third and more severe resolution has stalled - partly due to a U.S. intelligence report in early December that Iran halted a secret nuclear weapons program in 2003.

U.S. officials say Iran's effort to perfect uranium enrichment would allow it to easily resume a weapons program despite its professions of peaceful nuclear intent.

The State Department confirmed Wednesday that Secretary of State Condoleezza Rice will join foreign minister counterparts from the other four permanent Security Council member countries and Germany in Berlin next Tuesday in an effort to work out a new resolution.

Secretary Rice has acknowledged tactical differences with Russia and China over a new resolution. But Spokesman McCormack said none among the so-called P Five Plus One group has backed away from the strategic objective of using sanctions to get Iran to change course.

Under-Secretary of State for Political Affairs Nicolas Burns discussed the Berlin meeting Wednesday in a telephone conference call with his P Five Plus One colleagues. McCormack said it was a good discussion but that an agreement is not yet in hand.