Iraqi Prime Minister Nouri Maliki has arrived in Jordan's capital, Amman, for talks with US President George W Bush.

They are expected to discuss how to improve the security situation in Iraq, following some of the worst violence since the US-led invasion in 2003.

In Iraq, the political group loyal to Shia cleric Moqtada al-Sadr has said it is suspending its participation in the government and the parliament.

It said the move was in protest at the Mr Maliki's visit to Jordan.

In a statement, the group said Mr Maliki's meeting was a provocation to the Iraqi people and a violation of their constitutional rights

President Bush, who is going to Amman from the Nato summit in Latvia, is expected to give public support to Mr Maliki, but privately will be renewing pressure on him to take action against Shia militias, says the BBC's Jon Leyne in Amman.

The two leaders will also discuss moves to transfer more responsibility to Iraq's security forces.

Iraqi President Jalal Talabani, who has extended a visit to the Iranian capital, urged Tehran to back the elected Iraqi government, not Shia militia groups.

Memo revealed

On the eve of the Amman meeting, Jordan's King Abdullah told the BBC Arabic Service he was very concerned about increasing violence in Iraq and urged Iraqi leaders not to let their country disintegrate.

"We have warned, from the start and on more than one occasion, of the danger of turning a political dispute into a sectarian and religious conflict among the people of one religion and one country," he said.

"We [urge] our brothers in Iraq, the Iraqi political and religious leadership - be they Shia or Sunni - to realize the seriousness of the situation and not to allow any conspiracy to pass aimed at dividing or destroying Iraq in a whirlpool of violence and chaos."

Meanwhile, the New York Times newspaper has published details of a memo in which Mr Bush's national security adviser, Stephen Hadley, raises doubts about Mr Maliki's ability to control sectarian violence.

According to the Times, the 8 November memo to top US officials recommends that the White House take extra steps to strengthen Mr Maliki's hand.

"His [Mr Maliki's] intentions seem good when he talks to the Americans, and sensitive reporting suggests he is trying to stand up to the Shia hierarchy and force positive change", the memo says.

"But the reality on the streets of Baghdad suggests Maliki is either ignorant of what is going on, misrepresenting his intentions or that his capabilities are not yet sufficient to turn his good intentions into actions."

White House spokesman Tony Snow, traveling with Mr Bush, said the chief aim of the memo was "to support Maliki and enhance his capabilities".

New level of violence

The Amman summit follows one of the bloodiest weeks in Iraq since the American-led invasion in 2003.

Mr Bush is facing growing political pressure over the lack of progress in Iraq and the rising tide of violence, says the BBC's Jonathan Beale in Washington.

Even the White House acknowledges the violence has reached a new phase, though it still dismisses talk of a civil war, he says.

Mr Bush is also under pressure to redouble US efforts to resolve the Israeli-Palestinian conflict, our correspondent says, and will be told by King Abdullah that it is the most pressing crisis in the region.

Even Washington's strongest Arab allies are showing signs of frustration at US policies in the Middle East, he adds.

Photo Caption

Nouri Maliki, the Iraqi Prime Minister