Rocket fire interrupted the swearing-in ceremony Monday for Afghan President Ashraf Ghani, whose second-term win has been undercut by his rival simultaneously claiming the premiership ahead of critical peace talks with the Taliban.

The bitter feud between Ghani and his former chief executive Abdullah Abdullah has raised fresh fears for Afghanistan's fragile democracy just as the US prepares to leave the country following an agreement last month with a resurgent Taliban.

Polls were held in September, but repeated delays and accusations of widespread voter fraud meant that Ghani, the incumbent, was only narrowly declared the winner in February -- sparking a furious response from Abdullah, who vowed to form his own parallel government.

On Monday Ghani, dressed in traditional Afghan clothing and white turban, arrived at the presidential palace to be sworn in, surrounded by supporters, senior political figures and foreign dignitaries including US special envoy Zalmay Khalilzad and General Scott Miller, who heads US forces in Afghanistan.

Minutes later, in another corner of the sprawling palace compound, a suit-clad Abdullah inaugurated himself as president, vowing to "safeguard the independence, national sovereignty, territorial integrity" of Afghanistan. As hundreds of people watched Ghani's ceremony, at least two loud explosions were heard, prompting some to flee.

The interior ministry later said the blasts were caused by four rockets that struck downtown Kabul including the wall of the Serena luxury hotel located near the presidential palace. No deaths were reported but "one police officer was slightly injured", ministry spokesman Nasrat Rahimi said.

The Islamic State group claimed the blasts, which mirrored a similar incident targeting a Ghani speech in August 2018 that injured six civilians. "I have no bulletproof vest on, only my shirt," Ghani told those who stayed behind as sirens wailed. "I will stay even if I have to sacrifice my head."

An AFP reporter saw many of those who fled return to their seats after Ghani's refusal to leave the podium prompted cheers and applause.

Game of thrones

The game of thrones has strained the patience of the international community and Afghans alike, with Washington warning earlier that the bickering posed a risk to the US withdrawal deal, which requires the Taliban to hold talks with Kabul.

Widening divisions among Afghan politicians would leave the insurgents with the upper hand in those negotiations. The intra-Afghan talks were due to begin on Tuesday but Ghani's government has not released any details of the negotiating team and it is unclear when they may start.

Abdullah said Monday that he would send a separate group to talk to the Taliban. "One of the first priorities of our government would be to create political consensus, and appoint a negotiating team," he said.

The row has left many Afghans despairing for their country's future. "It is impossible to have two presidents in one country," said Ahmad Jawed, 22, who urged the men "to put their personal interests aside and only think of their country instead of fighting for power".

"Instead of holding oath-taking ceremonies they should talk to each other to find a solution," he told AFP.

During Monday's speech, Ghani appeared to extend an olive branch to his opponents, saying: "Today is the day for unity, we have to think about the future."

"I call on... (past) political rivals to lend me a hand and a shoulder to serve this country. Our mission is peace and ending the 40 years of war," he added.

'Only way forward'

Afghans have shown little enthusiasm for Abdullah, Ghani or the election process in general, with most abstaining in last year's lacklustre poll that saw candidates pitch few ideas or policies. Violence has continued unabated, except for during a week-long partial truce ahead of the US-Taliban deal.

In the deadliest attack to hit Afghanistan in weeks, IS gunmen shot dead 32 people and wounded dozens of others at a political rally in Kabul on Friday.  The Taliban, who have slammed the electoral process as "a fake and foreign-run" affair, have also ramped up attacks on Afghan forces and civilians.

The insurgents' spokesman Zabihullah Mujahid told AFP the competing ceremonies showed that "nothing is more important to the slaves than their personal interests". Experts say the infighting is likely to cost the government, which is already under pressure after being shut out of the Doha negotiations for the US-Taliban deal.

According to the agreement signed in Qatar, foreign troops will withdraw from Afghanistan in 14 months, in return for various security commitments from the Taliban and a pledge to hold talks with Kabul. Political analyst Atta Noori said the squabbling would "gravely affect the government's position in the upcoming intra-Afghan talks".

"Unity is the only way (forward) if they want to win on the negotiating table," he told AFP.