"The time for such a visit has not yet come," foreign ministry spokesman Hamid Reza Asefi told reporters, referring to a US offer to send a top delegation to discuss relief for victims of the December 26 earthquake in the southeastern city of Bam.

In addition to sending aid supplies and a medical team, Washington approached Tehran after the quake about the possibility of sending a delegation headed by top Republican Senator Elizabeth Dole.

The United States, which severed ties with Iran after the 1979 Islamic revolution, also suggested that a member of President George W. Bush's family might accompany Dole to show the importance he places on relief for the victims of the quake, which killed some 30,000 people.

But Asefi said the visit "was not on the cards".

"If the dominant view in the American leadership is to break the wall of suspicion and they practically move in this direction, there will be another climate," he told reporters.

"But in recent days we have heard different voices, so by consequence it is difficult to judge. It is not clear if this gesture is isolated or not," he added.

"The US knows what it has to do. Political and humanitarian questions should not be mixed."

On Friday, US State Department spokesman Adam Ereli said Washington understood the Iranian response and that the United States would not do anything that would compromise the humanitarian response to the quake survivors, about 40,000 of whom have been left homeless and are sleeping in tents.

He stressed that the US proposal had been intended to demonstrate "our compassion for the Iranian people", but cautioned that once the recovery operation moves forward a US humanitarian mission to Iran might no longer be necessary.

Had the mission proceeded, it would have been the first public official US visit to the Islamic nation since the 1979-1981 period, when 52 Americans were held hostage in Iran for 444 days and the two countries broke diplomatic relations.

In the wake of the quake, the US also eased sanctions on Iran in a gesture welcomed by powerful former Iranian president Akbar Hashemi Rafsanjani and Foreign Minister Kamal Kharazi.

Asefi also said this was a "positive" step, and said if the lifting was maintained better relations would follow.

"The lifting of the sanctions, even if temporary or partial, is positive because Iranians can send aid to their compatriots. If it is extended in time and on the types of products concerned, there will be a different climate," the spokesman said, adding the 90-day period was "not very long".

He said that conflicting messages from Washington were not helpful, but refused to say under what circumstances Iran would be willing to reopen dialogue.

US President George W. Bush said Thursday that his moves were a sign of compassion and not a message that he wants warmer ties with Iran, which he labeled as part of an "axis of evil" in 2002.

"What we're doing in Iran is we're showing the Iranian people (that) the American people care, that they've got great compassion for human suffering," the president told reporters in Texas.

And he made clear that if the Islamic republic wanted better relations, it had to turn over any followers of Osama bin Laden it has in custody, abandon its pursuit of nuclear weapons and embrace democratic political reform.

TERRA.WIRE