Afghanistan’s rival leaders were each sworn in as president in separate ceremonies, throwing plans for negotiations with the Taliban into chaos and creating a dilemma for the United States as it figures out how to move its peace deal with the Taliban forward.

The US-Taliban deal signed just over a week ago was touted as Washington’s effort to end 18 years of war in Afghanistan and was seen by many Afghans as the best opportunity yet for bringing an end to relentless wars.

But the sharpening dispute between President Ashraf Ghani, who was declared the winner of last September’s election, and his rival Abdullah Abdullah, who charged fraud in the vote along with the elections complaints commission, threatens to wreck the next key steps and even risks devolving into new violence.

The rivals held simultaneous inauguration ceremonies, each packed with his supporters, Mr Ghani’s in the presidential palace and Mr Abdullah’s next door in the Sapedar Palace.

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Washington’s peace envoy Zalmay Khalilzad attends the inauguration ceremony for Afghan President Ashraf Ghani(Rahmat Gul/AP)

Even as Mr Ghani was winding up his thank you speech, blasts of rocket fire were heard hitting near the presidential palace.

“We have seen bigger attacks. Don’t be afraid of just two blasts,” Mr Ghani said, raising his hands and urging rattled participants to stay in their seats.

The perpetrators of the fire were not immediately known, but the scene increased worries that the split will open the door to violence.

In a sign of international support for Mr Ghani, his ceremony, aired on state TV, was attended by Washington’s peace envoy Zalmay Khalilzad, General Austin S. Miller, the head of US forces in Afghanistan, as well as a number of foreign dignitaries including the US Embassy’s charge d’affaires and Tadamichi Yamamoto, the UN Secretary General’s personal representative to Afghanistan.

At Mr Abdullah’s inauguration, aired on private Tolo TV, among those present were so called “jihadi’ commanders, who participated in the brutal civil war of the 1990s and were among those who allied with the US-led coalition to topple the Taliban in 2001.

Both candidates, but particularly Mr Abdullah, are backed by warlords with heavily armed militias, underscoring fears they could use force to back their candidate.

The rival claims to be president have the potential to further split and weaken Afghanistan’s fragile institutions, including the military, if they demand their authority be recognised.

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Afghan President Ashraf Ghani, right, shakes hands with Chief Justice Sayed Yousuf Halim, left, after being sworn in (Rahmat Gul/AP)

When Washington and the Taliban insurgents signed their accord on February 29, the next crucial step was to be intra-Afghan talks in which all factions including the Taliban would negotiate a road map for their country’s future.

They are looking to hammer out such thorny issues as women’s rights, free speech and the fate of tens of thousands of armed men on both sides of the 18-year war.

Those negotiations were set to be held Tuesday in Oslo, but the political chaos in Kabul makes it a near impossibility.

Mr Ghani said he will announce his team Tuesday, though it appears Mr Abdullah may also announce his negotiating team.

At the duelling inaugurations, both men offered their peace plan.

Mr Abdullah said he had no preconditions for talks and promised his team would be inclusive, but did not elaborate.

Mr Ghani said he understood that another promise of a reduction of violence would come from the Taliban in exchange for the release of their prisoners.

There was no comment from the Taliban to this and previously they said their earlier commitment was only for seven days and a cease fire would be part of negotiations.

The US has said its troop withdrawal from Afghanistan over an 18-month period provided for in the deal will be linked to the Taliban keeping their counter-terrorism promises, but not to the success of talks between the Taliban and the Afghan government

Afghanistan’s election commission declared incumbent Mr Ghani as the winner of September’s vote.

His former partner in a unity government, chief executive Mr Abdullah, as well as the election complaints commission say the results are fraught with irregularities.

As a result, both Mr Ghani and Mr Abdullah declared themselves winners.

The duelling inaugurations took place despite last-minute shuttle diplomacy by Mr Khalilzad, who reportedly went back and forth between the two Afghan rivals into the early hours Monday.

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General Austin S. Miller attended the ceremony (Rahmat Gul/AP)

He asked both sides to delay their inaugurations three days to sort out the stalemate, a senior member of Abdullah’s team, Basir Salangi, told Tolo TV.

Mr Abdullah reportedly said he was ready, but only if Mr Ghani also agreed.

Taliban spokesman Zabihullah Mujahed said late on Sunday that the Taliban were still committed to the deal, but said the duelling presidential inaugurations “are not good for the Afghan nation”.

Until now the Taliban have refused to sit with Mr Ghani’s government.

There was no immediate comment from the Taliban.

As well as competing candidates, Mr Khalilzad still has to get some agreement on a prisoner release, which was supposed to be settled before the intra-Afghan negotiations could begin.

The US-Taliban deal said 5,000 Taliban prisoners and up to 1,000 captives from the government side would be freed as a goodwill gesture ahead of the talks.