KABUL: Two powerful explosions on Saturday ripped through crowds of minority Hazaras in Kabul who had gathered to protest over a power line, killing at least 80 people and leaving 231 others wounded, Afghan public health ministry said.

Islamic State group claimed responsibility for twin explosions. The bombings, apparently aimed at sowing sectarian discord in a country well known for Shia-Sunni harmony, came as thousands of Hazaras gathered to protest over a multi-million-dollar power line.

“As a result of the attack 80 people were martyred and 231 others were wounded,” the interior ministry said in a statement.

“Based on initial information, the attack was carried out by three suicide bombers... The third attacker was gunned down by security forces.”

The Taliban, who are in the middle of their annual summer offensive and are more powerful than IS, strongly denied any involvement in the attack.

IS claimed the bombings in a statement carried by its affiliated Amaq news agency, calling it an attack on Shias.

One of the march organisers Laila Mohammadi said she arrived at the scene soon after the blast and saw “many dead and wounded people”.

'Horrific attack'

The attack came as thousands of demonstrators gathered to demand that a multi-million-dollar power line pass through their electricity-starved province of Bamiyan, one of the most deprived areas of Afghanistan with a large Hazara population.

“The horrific attack on a group of peaceful protestors in Kabul demonstrates the utter disregard that armed groups have for human life,” Amnesty International said in a statement.

Footage on Afghan television and photographs posted on social media showed a scene of carnage, with numerous bodies and body parts spread across the square.

Seddq Sediqqi, spokesman for the Ministry of Interior, said police were working to confirm initial reports of the blast.

Violence had been feared at what was the second demonstration by Hazaras over the power line issue. The last one in May attracted tens of thousands of people, also shutting down the central business district.

“Such attacks are a reminder that the conflict in Afghanistan is not winding down, as some believe, but escalating, with consequences for the human rights situation in the country that should alarm us all.”

In a statement, Afghan President Ashraf Ghani said he was “deeply saddened” by the carnage, adding that the casualties included security officials.

“Holding protests is the right of every citizen of Afghanistan... but terrorists entered the protests, and carried out explosions that martyred and wounded a number of citizens including members of security forces,” the presidential palace said.

It was attended by Hazara political leaders, who were notable by their absence on Saturday. At the height of the march, demonstrators chanted slogans against President Ashraf Ghani and Chief Executive Abdullah Abdullah, shouted “death to discrimination” and “all Afghans are equal”.

The so-called TUTAP line is backed by the Asian Development Bank with involvement of Turkmenistan, Uzbekistan, Tajikistan, Afghanistan and Pakistan. The original plan routed the line through Bamiyan province, in the central highlands, where most of the country's Hazaras live.

That route was changed in 2013 by the previous Afghan government. Leaders of the marches have said that the rerouting was evidence of bias against the Hazara community, which accounts for up to 15 per cent of Afghanistan's estimated 30 million-strong population.

They are considered the poorest of the country's ethnic groups, and often complain of discrimination. Bamiyan is poverty stricken, though it is largely peaceful and has potential as a tourist destination.

Afghanistan is desperately short of power, with less than 40 per cent of the population connected to the national grid, according to the World Bank. Almost 75 per cent of electricity is imported.