Iran's hard-line government, accused by the White House of harboring top al-Qaeda members, poses a big problem for the US and should be replaced, US lawmakers said on Sunday.
Democrats and Republicans urged extreme care in working toward that end, in order to avoid fomenting an anti-American reaction among Iranians who admire the US way of life.
In Tehran, Iran's foreign minister insisted his country does not and would not shelter al-Qaeda terrorists, and even has jailed some members of Osama bin Laden's network and plans to prosecute them.
"Iran has been the pioneer in fighting al-Qaeda terrorists, who have been posing threats to our national interests," Foreign Minister Kamal Kharrazi told the government's Tehran Television. "Iran was al-Qaeda's enemy before the US"
The Washington Post reported on Sunday that the administration has cut off contacts with Iran and "appears ready to embrace an aggressive policy of trying to destabilize the Iranian government."
Asked about the report, White House spokesman Scott McClellan said: "No, our policy continues to be the same."
The US insists that Iran stop supporting terrorists and end illicit weapons programs, he said.
"Iran knows what it needs to do," he said.
Worry about possible activities of senior al-Qaeda operatives thought to be in Iran was a factor in raising the domestic terror alert level in the US last week, officials have said. Those operatives are suspected of being connected to the recent bombings in Saudi Arabia and Morocco.
"There's no question but that there have been and are today senior al-Qaeda leaders in Iran, and they are busy," Defense Secretary Donald Rumsfeld said last week.
Nonetheless, US officials are finding ways of communicating with Iranian officials "on subjects that are important to us," the US Department of State said last week.
One issue is Iran's suspected development of nuclear weapons. Washington rejects Iran's contention that its nuclear activities are for peaceful purposes.
Representative Porter Goss, chairman of the House Intelligence Committee, said Iran has shown some cooperation on terrorism, but not enough.
"The trick in Iran is this: The good guys are trying to bring some reform; the bad guys control the levers of power. Sorting the two apart and then isolating the bad guys and taking the levers of power away from them is what's got to happen," Goss said on CBS' Face the Nation.
"It's got to happen in a way that does not shut down the reformists or cause repercussions to the reformists. This is hard," he said.
The US has labeled Iran as an exporter of terrorism since Washington began drawing up such a list in 1979 -- the year the Islamic republic was founded and then sponsored the seizure of the US Embassy. Fifty-two Americans were held hostage for 444 days, and US-Iran relations have remained severed.
Lawmakers in favor of a new government in Iran did not advocate a military solution.
Representative Jane Harman of California, ranking Democrat on Goss' committee, said she considered Iran "more of a clear and present danger than Iraq last year" but wants a diplomatic focus.
Senator Joe Lieberman, a Democratic presidential hopeful who strongly backed the Iraq war, said "regime change" is the answer in Iran. He said he was not suggesting US military action because of the pro-American attitudes of many Iranians.