Supporters of Afghan presidential candidate Abdullah Abdullah marched through Kabul as fears grow of unrest erupting over alleged fraud in the election. (Shah Marai/AFP/Getty Images)

— Supporters of Afghan presidential candidate Abdullah Abdullah took to the streets of the capital Saturday to protest alleged electoral fraud and what they say is the government’s failure to take it seriously.

The demonstrations were small and peaceful, but the participants promised violence if their demands aren’t met.

Abdullah, a former foreign minister, has already rejected the official election results, weeks before they were due to be released, because he says they will be distorted by fraud.

He has asked the United Nations to oversee the vote-counting process and criticized Afghan President Hamid Karzai for colluding with his opponent, Ashraf Ghani.

Abdullah’s stance prompted concerns of civil unrest, as thousands of his supporters promised not to recognize the next president if it’s not Abdullah.

Saturday marked the first day of demonstrations but certainly not the last.

“Death to the Independent Election Commission,” the protesters, mostly young men, chanted through megaphones. By early afternoon, they had blocked several main thoroughfares.

“If the government doesn’t accept our demands, we will fight, and we will destroy everything,” said Kawoos Waqif, a 26-year-old engineer.

Karzai, who met this week with Jan Kubis, the top U.N. representative in Afghanistan, backed Abdullah’s suggestion of additional U.N. oversight.

“Any source that can help Afghanistan on this issue is appreciated,” said a statement released Friday from the Afghan palace.

The United Nations, along with the United States, has long emphasized the important role played by the country’s Independent Election Commission but is searching for an alternative or a backstop that would satisfy Abdullah and still yield an accurate vote count.

“We want to reassure the Afghan people that we stand ready to assist them and to support them in resolving this political impasse,” said Nicholas Haysom, the U.N. deputy special representative for Afghanistan.

Haysom expressed concern about the prospect of violent demonstrations, which could “lead to a spiral of instability.”

The exact role the United Nations might play remains unclear, but it could serve as an additional check on the election commission’s work. Much of Abdullah’s anger has been targeted at Zia ul-Haq Amerkhel, a top elections official whom he has accused of being biased in favor of Ghani.

Meanwhile, the head of that commission, Yusef Nuristani, said he will continue calculating results from the June 14 vote in spite of Abdullah’s refusal to accept the commission’s work as legitimate.

Preliminary results were initially supposed to be released July 2, but Nuristani said that announcement would be “delayed for a few days to ensure more transparency.”

While protesters marched in Kabul, chanting defiant slogans, other Abdullah supporters went about their lives, bemused by the anger that had gripped some of their countrymen.

“Yes, I voted for Abdullah, but I know a protest only hurts the economy,” said Zahir, a vegetable seller who, like many Afghans, goes by only one name. “I’m 65. I’ve seen 10 different rulers but haven’t received a benefit from any of them.”

Mohammad Sharif and Sayed Salahuddin contributed to this report.