The White House confirmed that Washington had approached Tehran about sending a delegation but would not describe its possible composition, which the senior official said may include a member of President George W. Bush's family.

"The idea of sending a delegation to Iran is one of several under consideration," said White House spokeswoman Claire Buchan in Crawford, Texas where Bush is relaxing on his ranch.

"We have not heard back from the Iranians on it," she said, adding that it would be premature to discuss the members of the delegation until Iran responded to the proposal.

"Let's wait and see until the Iranians are receptive to a delegation first before we discuss who might be in," Buchan said.

Earlier, the senior US official said the prospects for Iranian approval of the mission -- the latest in a series of US overtures to Iran since the earthquake that killed some 30,000 people in the southeastern city of Bam -- were unclear and that the trip was far from certain.

"This is an idea that's being looked at, but, frankly, the Iranians aren't jumping on it the way they jumped on the assistance," the official said, referring to Iran's near immediate acceptance of US aid after the quake.

"It's still in play, but we haven't heard back from the Iranians and it would be premature for them to start packing bags," the official told AFP on condition of anonymity.

The official said Dole, a former head of the American Red Cross, had asked the State Department to let her travel to Iran with a Red Cross delegation and that her request had been received favorably.

The Washington Post, which first reported the offer citing unidentified US and Iranian officials, said the proposal was presented to Iran on Tuesday.

The senior official stressed that the mission would be humanitarian and not diplomatic although the proposal comes amid new US overtures to Iran in the aftermath of the earthquake.

In addition to the offer of assistance last week, the Bush administration on Wednesday temporarily eased US restrictions on sending money and sensitive equipment to Iran.

Bush said on Thursday that the moves were a sign of compassion and not a message that he wants warmer ties with Iran, which he labelled 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 wants better relations, it must turn over any followers of Osama bin Laden it has in custody, abandon its pursuit of nuclear weapons and embrace democratic political reform.

Should the Dole mission proceed, it would be the first public official US visit to the Islamic nation since the 1979-81 period, when 52 Americans were held hostage in Iran for 444 days and the two countries broke diplomatic relations.

Iranian President Mohammad Khatami has stressed that any US humanitarian help, while welcome, was not indicative of warming diplomatic relations between the two nations.

Iran's foreign minister, Kamal Kharazi, on Thursday hailed the easing of sanctions as "positive" but said that only their total lifting would create a new climate between Tehran and Washington.

Dole, a Republican from North Carolina, is a former secretary of labor and transportation and is married to former Senate majority leader and 1996 Republican presidential candidate Bob Dole.

TERRA.WIRE