U.S. Secretary of State Hillary Clinton said on Wednesday that Washington might consider consulting Iran over Afghanistan but accused Tehran of interference in the Middle East.

Speaking to reporters en route to Brussels, Clinton said Iran posed a serious threat because of its nuclear plans and alleged funding of "terrorism", but that Washington was looking for areas where it could engage with Tehran, including on Afghanistan, if such talks were useful.

"Where it is appropriate and useful for the United States and others to see whether Iran can be constructive, that will be considered," Clinton said, when asked directly whether the United States could consult Iran over Afghanistan.

Iran borders Afghanistan and worked closely with the United States after the U.S. military offensive there to topple the Taliban and fight al Qaeda following the Sept. 11, 2001 attacks on New York and Washington.

"In the early days of the military efforts by the United States and our allies to go after the Taliban and al Qaeda, Iran was consulting with our ambassador on a daily basis," she said.

In a turnaround from Bush administration policy, President Barack Obama has said the United States would be prepared to engage Iran, although Clinton told Arab ministers gathered in Egypt this week that she was doubtful Iran would respond to diplomatic overtures, a senior State Department official said.

Analysts and diplomats have predicted that a dialogue with Iran could begin on issues such as Afghanistan, where the United States is trying to turn around a war it is losing and plans to send in additional 17,000 troops.

Clinton told reporters that "over and over and over again" Arab ministers she met in Egypt, as well Israeli politicians and Western-backed Palestinian President Mahmoud Abbas, had voiced concern to her this week over Iran's meddling in the region.

"It is clear that Iran intends to interfere with the internal affairs of all of these people and try to continue their efforts to fund terrorism whether it is Hezbollah or other proxies. We have said consistently that we are ready to engage but we want to make sure it is constructive and that goes for Afghanistan and it goes for all the rest of the region," she said.

At a news conference in Ramallah with Clinton, Abbas directly pointed a finger at Iran and accused its leaders of undermining the Palestinian Authority, which rules the Israeli-occupied West Bank while Hamas runs the Gaza Strip.

"I am not going to add to what President Abbas said. I think he spoke forcefully, on behalf of his government and the Palestinian people," Clinton said.