Ahmadinejad's letter came at a time of heightened tension

In it, Mr Ahmadinejad criticises the US invasion of Iraq and urges Mr Bush to return to religious principles.

US Secretary of State Condoleezza Rice dismissed the letter as "offering nothing new" and the White House said there would be no formal written reply.

The letter came as foreign ministers met for talks on Iran's nuclear crisis.

But after three hours of discussions in New York, the ministers failed to agree on how to tackle the problem of Iran's atomic programme.

Iraq 'lies'

The letter - thought to be the first from an Iranian president to a US leader since Iran's 1979 revolution - sparked intense interest, coming at a time of tense relations between Washington and Tehran.

I have been thinking, how one can justify the undeniable contradictions that exist in the international arena

Ahmadinejad letter in full (75k) Most computers will open PDF documents automatically, but you may need to download Adobe Acrobat Reader. Download the reader here

The 18-page document has not yet been made public, but according to leaks, Mr Ahmadinejad spoke of the invasion of Iraq, and a range of other issues.

"Lies were told in the Iraqi matter," Reuters news agency quoted the letter as saying. "What was the result? I have no doubt that telling lies is reprehensible in any culture."

The president also questioned the creation of Israel, asking "how can this phenomenon be rationalised or explained?", Reuters reported.

In an apparent allusion to Iran's nuclear programme, Mr Ahmadinejad is quoted by the Associated Press as asking: "Is not scientific R&D [research and development] one of the basic rights of nations?"

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"Why have the various aspects of the attacks been kept secret? Why are we not told who botched their responsibilities?" he asks.

The president ends the letter by appealing to Mr Bush to return to religion.

"We increasingly see that people around the world are flocking towards a main focal point - that is the Almighty God.

"My question for you is, 'Do you not want to join them?'"

Divisions exposed

There would not be a written response to President Ahmadinejad, National Security Council spokesman Frederick Jones told the AFP news agency.

"We've already given our response," he said, referring to the swift dismissal by US officials of the letter as a ploy which contributed nothing towards helping resolve the stand-off over Iran's nuclear programme.

The US is pushing for a decisive resolution

Hours after the letter was sent, Ms Rice held an inconclusive meeting with her UN Security Council counterparts and the German foreign minister on what action to take over Iran.

BBC diplomatic correspondent James Robbins says that far from drawing the key powers at the UN towards agreement on the issue, the meeting seems to have exposed the scale of division.

The UK's newly-appointed foreign minister, Margaret Beckett, acknowledged the meeting had been difficult.

She refused to repeat her predecessor Jack Straw's insistence that military action against Iran was inconceivable.

Mrs Beckett said she preferred to make clear that no-one was discussing military action. This language, our correspondent says, was far more welcome to the Americans.

After the meeting, an unnamed senior US state department official said prospects for an agreement this week on a UN Security Council resolution were "not substantially good".

However, the official said the US was "very satisfied and confident" at this stage.

Washington has pushed for any resolution to be adopted under the terms of Chapter Seven of the UN Charter.

These are binding on all UN members, but do not automatically lead to sanctions or military action. Further decisions would be needed for such measures.

But China and Russia have resisted such a move, fearing it could lead to a new war.