Afghanistan is increasingly relying on “cheap but dangerous” pro-government militias, some of whom have committed serious abuses in the communities they protect, an international research group said Thursday.

The International Crisis Group said members of the 30,000-strong Afghan Local Police have killed civilians and committed fraud, theft, rape, kidnapping, drug trafficking and extortion.

The government has come to rely on the militias as it struggles to fend off attacks from the Taliban. The insurgents launched their annual spring offensive in April – the first since the U.S. and NATO forces formally ended their combat mission at the end of last year.

The ALP is a pro-government militia which emerged from U.S. efforts to mobilize rural communities against the Taliban. Now, the militiamen fight on the front lines, losing men at three to six times the rate of soldiers and police while costing $120 million per year, the group said.

However, the militiamen are increasingly acting as vigilantes and power brokers in the areas they are supposed to protect, and the government is finding it hard to rein them in, the group said, citing unnamed officials.

The report said that about 20 percent of U.S. special forces teams mentoring ALP units in 2011 reported ALP members committing physical abuse and violence; 12 percent reported bribe-taking. They also reported salary fraud, theft, rape, drug trafficking, and abuse, as well as selling or renting ALP weapons and vehicles.

A unit in the northern Faryab province was accused of rape, looting and using a dry well filled with snakes as a torture chamber, the ICG said.

In 2014, the United Nations recorded 53 civilians killed by pro-government militias, almost triple the 2013 number.

The ICG said the presence of the militiamen had not made communities safer, noting that in the five provinces without an ALP presence violence declined by 27 percent between 2010 and 2014. In the country as a whole during that period violence spiked 14 percent.

And in the northern Kunduz province, where the Taliban launched a major assault in April that almost saw them seize the provincial capital, the ICG report said ALP abuses had led residents to chase the militiamen out of some areas, clearing the way for the Taliban to advance.

The ICG report urged the Afghan government to strengthen oversight of the ALP, with regular reports on performance including human rights abuses. It said Kabul should also identify units that worsen security, reducing and eliminating them, and should not expand the program.

The Associated Press contributed to this report.