WASHINGTON • The United States has voiced optimism about reaching an accord to end the war in Afghanistan as a partial truce held with the Taleban, warning rival leaders in the Kabul government not to scuttle the "enormous opportunity".

The US plans to sign an agreement with the Taleban on Saturday in Qatar if the week-long truce holds. Since the truce last Saturday, the number of Taleban attacks has fallen dramatically.

"So far, the reduction in violence is working - imperfect, but it's working," US Secretary of State Mike Pompeo told a news conference in Washington on Tuesday. "We're on the cusp of an enormous, enormous political opportunity."

The historic deal would see the US withdraw thousands of troops, winding down America's longest war, which was launched after the Sept 11, 2001, attacks but has grown increasingly unpopular at home.

The Taleban would then open negotiations with the internationally recognised government in Kabul, which the Islamist militants have refused to recognise.

But the Afghan administration is in disarray. President Ashraf Ghani was last week declared the winner of a new term in an election, but his chief rival, Mr Abdullah Abdullah, rejected the results and vowed to form his own government.

The US has conspicuously not congratulated Mr Ghani, in contrast to the European Union and the Kabul government's regional ally, India.

In a statement on Tuesday, the State Department said only that it "notes" the election announcement. It said Mr Ghani had agreed to postpone his inauguration, which was scheduled for today.

Mr Abdullah's spokesman, Mr Fraidoon Khwazoon, told AFP that both Mr Abdullah and Mr Ghani were delaying by two weeks the swearing-in ceremonies planned.

Asked about the election, Mr Pompeo said the US wanted to make sure the results were "free and fair and accurate", and warned against "any one small group" blocking the peace process.

"There are those with an enormous vested interest in the status quo," Mr Pompeo said, characterising the current situation as "bloodshed, tears, economic challenges".

"We want to make sure that... all the people who have an interest - whether that's because of corruption or because of some ideological view - cannot spoil what it is that the Afghan people so richly deserve," he added.

Mr Ghani, while saying he hopes for peace with the Taleban, was critical as diplomacy gathered steam last year, especially over the militants' refusal to recognise the Kabul government.

US President Donald Trump has called the Afghan war a waste of blood, and his administration has called the truce a test of whether the Taleban can make good on its promises.

The key US demand remains the same from 2001 - that the Taleban not allow Afghan territory to be used by Al-Qaeda, or Islamic State in Iraq and Syria (ISIS) extremists, to plan international attacks.

Mr Pompeo rejected a question on whether a US withdrawal would jeopardise the rights of women, who under the Taleban's ultra-austere regime from 1996 to 2001 were forbidden education and forced to wear all-encompassing burqas in public. "Our mission set there has been much broader than that," Mr Pompeo said.

He voiced confidence that "voices all across the Afghan political spectrum", including women, "will go into the ultimate solution".

Mr Trump, speaking to reporters on a visit to India, said the US was "pretty close" to a deal.

He complained that US troops had turned into a "police force" rather than pursuing a military goal. "We could win that easily if I wanted to kill millions of people. I don't want to kill millions of people, innocent people," he said.

US General Scott Miller, the commander of the Nato-led mission in Afghanistan, also saw the partial truce succeeding. "We're seeing what we would call a downward trend in violence, which is great for the Afghan people. It's great for the country of Afghanistan," he said in a statement.

An Afghan security source told AFP that Taleban attacks had dropped from an average of 75 a day to about 15 since the truce began.

But underscoring the fragility of the situation, the Interior Ministry said five security personnel were killed in three attacks in rural areas on Tuesday.

US forces also announced the deaths of four ISIS members in two air strikes in Kunar province.

More than 100,000 Afghan civilians have been killed or injured over the past decade, according to the United Nations.

AGENCE FRANCE-PRESSE