A US government watchdog has filed a secret report to Congress into allegations of child sex abuse by the Afghan security forces ─ and the extent to which America holds them accountable.

According to the office of the Special Inspector General for Afghanistan Reconstruction (Sigar), which on Tuesday announced it had sent the classified findings to lawmakers, Afghan officials are failing to stop sexual exploitation.

Primarily at issue is the entrenched custom of what is known in Afghanistan as “bacha bazi” ─ or the sexual abuse of boys ─ and whether the US is turning a blind eye.

“Afghan officials remain complicit, especially in the sexual exploitation and recruitment of children by Afghan security forces,” Sigar said in a quarterly publication that described the outline of the Congressional report.

It states that the Afghan government has failed to identify or help victims. In some cases, the Afghan government arrested and prosecuted trafficking victims as criminals.

“Victim-protection efforts remained inadequate, as all but one government-run shelter for trafficking victims remained closed during the reporting period,” Sigar said.

Neither the Pentagon nor the Afghan government immediately responded to requests for comment.

Under US rules called the Leahy Laws, the Pentagon and the State Department are barred from providing assistance to any unit of a foreign nation's security forces if credible information exists that the unit has committed a gross violation of human rights.

Nato forces headed by the US provide training, equipment and other assistance across the Afghan security forces.

Impunity

Bacha bazi is not seen as homosexuality in Afghanistan, where gender segregation is rampant ─ instead the possession of young boys decked out as pretty women symbolizes power and primacy.

President Ashraf Ghani this year laid out stringent penalties against bacha bazi for the first time in a revised penal code, but the government has given no timeframe over when they will be enforced.

The new rules came after AFP last year exposed how the Taliban exploit bacha bazi to infiltrate security ranks.

The AFP story detailed how Taliban insurgents are using children to mount crippling insider attacks that have killed hundreds of police in southern Afghanistan over the previous two years.

Sigar said it had asked the Pentagon to declassify the report.

Stalemate

Sigar's latest quarterly report comes as the Afghan security forces continue to struggle against a resurgent Taliban, and US generals have said the situation is at a stalemate at best.

It lists a litany of shortcomings in Afghan governance and US oversight, and previous reports have found that billions of dollars in US reconstruction money are being poorly overseen and waste is rampant.

In what spells trouble for the Pentagon, the report also found that Afghan security forces continued to be slain at a high rate between January 1 and May 8, with 2,531 killed in action and another 4,238 wounded.

That toll continues a deadly trend from the start of 2015, when the Afghans succeeded Nato in providing security for the country.

It means Afghan forces are on course to suffer a similar amount of fatalities as last year, when more than 6,785 were killed.

After six months in office, President Donald Trump still hasn't announced whether he will send additional troops to Afghanistan to try to break the impasse with the Taliban.

In further signs of a continued stalemate, the amount of land held by the Afghan government remained at 59.7 per cent compared to land held by the Taliban or otherwise contested. That's the same ratio as during the previous quarter.