KANDAHAR, Afghanistan (Reuters) - A week of fighting between Taliban militants and fighters loyal to a commander from the mainly Shi’ite Hazara minority has heightened fears of a dangerous new phase of sectarian violence in Afghanistan.

The clashes in the central province of Uruzgan, which have killed at least 21 people, have highlighted concerns that Hazaras, members of a mainly Shi’ite Persian-speaking minority targeted by Islamic State attacks over recent years, may take up arms in frustration at a lack of action by the government.

While the Taliban, made up mainly of ethnic Pashtun Sunni Muslims, has not explicitly targeted Hazaras in the past, officials fear the violence could escalate into an ethnic battle.

“The fighting is very intense and is now becoming an issue of ethnic violence between Hazara and Pashtun,” said Amir Mohammad Barekzai, the provincial council chief. “The government must arrange a truce between them or there will be a massacre.”

Sectarian violence had until recent years been relatively uncommon in Afghanistan but suicide bombings at Shi’ite mosques and cultural centers by Islamic State as well as attacks on Hazaras traveling on provincial highways have fueled growing anger. Many Hazaras blame Sunni Pashtuns for the attacks.

Afghan and Western security officials, fearing the kind of sectarian violence that has devastated Iraq, have been deeply concerned that Hazaras who fought in Iranian-backed militias in Syria could hit Sunni targets.

TAX ROW SPARKS VIOLENCE

The recent violence started when Taliban fighters attacked a remote cluster of Hazara villages in Uruzgan province after they refused to pay tax to the insurgents, provincial officials said.

The Hazara commander, Abdul Hakim Shujaee, a former leader in the U.S.-funded Afghan Local Police, has been accused of serious human rights abuses and faces an arrest order from the central government, which has struggled to impose its authority on remote parts of the country.

He commands hundreds of Hazara fighters and remains free because of his connections with powerful political figures in Kabul, local officials say.

Uruzgan, squeezed between the Taliban heartlands of Kandahar and Helmand and the Hazara-dominated province of Daikondi, is home to both Pashtuns and Hazara families and the two groups have long had an uneasy co-existence.

Asadullah Sayed, the governor of Uruzgan, said fighting broke out between two armed groups in three villages of Khas Uruzgan district last week and government forces have been deployed to end the conflict.

He put the number of dead at 21 but a government security official said 43 people had been killed so far on both sides, many more wounded and some 300 families have fled the area.

The Taliban normally collect taxes from local residents in areas under their control to fund their insurgency but Hazara families defied them, setting off a fierce gun battle, he said.

The case echoes a standoff last month in central Ghor province involving a prominent Hazara commander called Alipur, known as “Commander Sword”, seen by supporters as a kind of Robin Hood figure but denounced by the government as a bandit.