An errant US air raid has killed Afghan police in the southern province of Helmand, the US military and local officials said.

The aerial attack on a compound took place on Friday afternoon after Afghan police had retaken a checkpoint captured by the Taliban a day earlier in Gereshk district, north of the provincial capital Lashkar Gah.

"Sixteen Afghan policemen were killed including two commanders. Two other policemen were wounded," Omar Zwak, a spokesman for the governor of Helmand, told Al Jazeera.

"It was most probably a miscommunication or the coordinates were not correct, which resulted in the US air strikes. An investigation has been launched."

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A statement from the US military confirmed the killings, saying, "aerial fires resulted in the deaths of the friendly Afghan forces who were gathered in a compound."

The US military did not provide the number of casualties.

'We are not winning in Afghanistan right now'

The deaths of Afghan police came amid increased fighting in Helmand, a southern province.

The United States has carried out 52 air raids in Helmand over the past five days, including 10 in Gereshk on Thursday, according to the US military headquarters in Kabul.

Friday's incident underlines the complicated security situation in Afghanistan as President Donald Trump's administration weighs sending more troops as part of a new strategy for the region.

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Earlier this week, Afghan security forces backed by US aerial bombardment retook Nawa district south of Lashkar Gah.

The US has been fighting in Afghanistan for nearly 16 years.

In June, James Mattis, the US defence secretary, said: "We are not winning in Afghanistan right now."

Taliban leader's son conducts attack

On Thursday, the son of Taliban leader Mullah Haibatullah Akhunzada died after driving a vehicle laden with explosives into an Afghan military base in the town of Gereshk, Qari Yousaf Ahmadi, the Taliban's main spokesman for southern Afghanistan, said.

Ahmadi said Abdur Rahman had been a student of an Islamic school but had wanted to carry out a suicide attack. "He succeeded in his mission last Thursday," he said.

Taliban fighters drove three captured Humvee vehicles into checkpoints during heavy fighting around Gereshk.

One senior Taliban member, close to Haibatullah's family, said Abdur Rahman had enrolled as a suicide bomber before his father became leader of the Taliban last year and had insisted on continuing after his father took office.

Mullah Haibatullah took over leadership of the Taliban after his predecessor, Mullah Akhtar Mohammad Mansour died in a US drone attack in Pakistan in May 2016.

"Before this, a number of close relatives and family members of previous supreme leaders had conducted suicide bombings but Sheikh Haibatullah has become the first supreme leader whose son sacrificed his life," the senior Taliban member said.