Venezuela's security forces have engaged in a "pattern of serious abuses" against anti-government protesters, including the use of torture, with the apparent aim of punishing political dissent, Human Rights Watch said Monday.

In a damning report, the rights group said members of the Venezuelan attorney general's office and the judiciary in many cases "knew of, participated in, or otherwise tolerated abuses against protesters and detainees, including serious violations of their due process rights."

Venezuela has been convulsed by sometimes violent protests against the leftist government of President Nicolas Maduro that have left 41 people dead since mid February, almost all of them civilians.

Jose Miguel Vivanco, HRW's Americas director, said the pattern of abuse has created "one of the most serious crises in Venezuela in years."

An investigation conducted by HRW in Venezuela in March found what it said was "strong evidence" of rights abuses in 45 cases involving 150 civilians in Caracas and three states.

"What we found during our in-country investigation and subsequent research is a pattern of serious abuse," it said.

In at least 10 cases, "the abuses clearly constituted torture," the report said.

"In most of the cases we documented, security forces employed unlawful force, including shooting and severely beating unarmed individuals," it said.

"Nearly all of the victims were also arrested and, while in detention, subjected to physical and psychological abuse."

HRW said "security forces allowed armed pro-government gangs to assault unarmed civilians, and in some cases openly collaborated with them in the attacks, our research found."

The report noted that some protesters have used violence, throwing rocks and Molotov cocktails, and that security forces also have suffered deaths and injuries in connection with the protests.

But it said in the cases it had documented the evidence indicated that the victims of security force abuses were unarmed and nonviolent, and some of the worst abuses were committed against people who were not even participating in protests, or were already in detention.

"The nature and timing of many of these abuses -- as well as the frequent use of political epithets by the perpetrators -- suggest that their aim was not to enforce the law or disperse protests, but rather to punish people for their political views or perceived views," the report said.

In many instances, security forces appeared to be targeting individuals taking pictures or videotaping confrontations with protests, about half of whom were journalists, HRW said.