BAGHDAD & WASHINGTON - At least 6,599 civilians were killed across war-torn Iraq in the months of July and August, the United Nations said Wednesday.

In July at least 3,590 people were killed and in August 3,009 died in bloody attacks on civilians, according to the UN human rights report.

"The month of July witnessed an increase in the number of security related incidents resulting in an unprecedented number of civilians killed throughout the country," the report said.

"Although the number of killings decreased at the beginning of August, further increases were evident towards the end of the month in Baghdad and other governorates."

The country is in the grip of a bitter conflict between the newly empowered Shiite majority and the ousted Sunni Arab elite that has left thousands dead since February.

UN Secretary General Kofi Annan on Monday warned that Iraq was on the brink of all-out civil war.

Meanwhile, despite signs of wearing patience with Iraqi leaders and a call for "tough choices" in Baghdad, President George W. Bush said Wednesday he was still satisfied with Prime Minister Nuri al-Maliki.

Bush's comments coincided with whispers of concern over the Iraqi government in the US media, raging sectarian violence, and mounting political pressure for the White House over dimming prospects for a US troop drawdown.

"I'm impressed by (prime minister) Maliki. I've talked to him, I've seen the decision-making process that he's put in place," Bush told CNN in an interview.

Earlier, the White House dismissed reports Bush was losing faith with Maliki, which emerged a day after the president publicly reminded Iraqi leaders that they must fulfill their side of a bargain to retain US support.

"No, no, and no ... that's absolutely false," said White House spokesman Tony Snow, adding that top US brass in Baghdad was satisfied Maliki was making progress in cracking down on terrorism and fostering national reconciliation.

"It's also worth, again, reminding people who are trying to leap to conclusions, that the man has been in power for barely more than 100 days," Snow said.

A front page New York Times report Wednesday said senior US and Iraqi officials were beginning to doubt whether Maliki had the strength to hold Iraq together and to ward off civil war.

"The thing you hear most, is he never makes any decisions," a former senior official was quoted as saying on condition of anonymity, referring to Maliki.

"That drives Bush crazy. He doesn't take well to anyone who talks about getting something accomplished and then refuses to take the next step."

The report followed other signs the Bush administration, at the very least, wanted to remind Iraqi leaders that US troops will not remain indefinitely.

With America still paying in blood and treasure in Iraq, some in the US foreign policy community question whether talk of such failings may also signal a subtle bid to sketch a rationale for an eventual exit for US troops.

Bush said Tuesday alongside Iraqi President Jalal Talabani that Iraqis should know America was with them "so long as the government continues to make the tough choices necessary for peace to prevail."

He struck the same theme earlier at the United Nations General Assembly.

"We will not yield the future of your country to terrorists and extremists. In return, your leaders must rise to the challenges your country is facing, and make difficult choices to bring security and prosperity," Bush said.

Asked whether Bush was adopting "conditional love" for Iraq, a senior White House aide Tuesday denied his remarks represented a veiled warning.

"I don't think there was anything threatening about it. It was constructive," said Meghan O'Sullivan, deputy national security advisor for Iraq and Afghanistan.

"It reflects the reality that the Iraqis have a lot of difficult decisions to do, these are hard to decisions to make, and that we need to both encourage and urge them to take on these decisions."

Administration warnings were echoed on Tuesday by a bi-partisan Iraq Study Group, tasked by Bush with framing new policy options in the country.

"Time is short, the level of violence is great. The margins for error are narrow," said co-chair Lee Hamilton.

"The government of Iraq needs to show its own citizens soon and the citizens of the United States that it is deserving a continued support."

Iraqi's deputy prime minister Barham Saleh, in a speech in Washington last week after meeting top US officials, appeared to nod to US impatience.

"I must recognize that ultimately it is up to the Iraqis to resolve their country's problems," he said.

"Outsiders cannot deliver for us. The Iraqi leadership must assume responsibility and deal with those challenges and turn the tide."

With fears of civil war mounting, US analysts say Maliki's government must crack down on Shiite death squads, ensure Sunnis a viable role in government, and improve rudimentary essential services.