RABAT, Morocco — After landing at the Rabat airport in 2010, Zakaria Moumni, a former kickboxing world champion, was distressed when he was taken aside by security agents, arrested, blindfolded and taken on a ride under a blanket in the back seat of a car to a secret facility. He says he was held there for four days, during which he was deprived of food and water.

“There is no worse feeling than this hopelessness of being blindfolded and handcuffed naked without being able to control anything,” said Mr. Moumni, 34, who spoke from Paris, where he now lives. “They told me that I was in a slaughterhouse and that I was going to leave in small pieces.”

The facility where Mr. Moumni was taken, on Interior Ministry property in a forest in the city of Temara, a few miles south of Rabat, had been established years earlier as a black site for the Central Intelligence Agency to hold “enhanced interrogations” of terrorism suspects. But over the years after the Sept. 11, 2001 attacks, it proved to be a handy tool for the security forces of the Moroccan government as well.

The release of the United States Senate report on torture last month renewed debate about the merits of harsh interrogation techniques in fighting terrorism. But less attention has been paid to what human rights advocates call the damage the sites have done in their host countries, which they say have used them as a tool for terrorizing their political opponents.

“In the early 2000s, many beautiful speeches came from Washington on the necessity to democratize,” said Aboubakr Jamai, a Moroccan journalist and international relations professor at IAU College in Aix-en-Provence, France. “They were meaningless because at the same time the C.I.A. was sending people to get tortured in Morocco.”

Senate Democrats said in their report that the C.I.A.’s harsh interrogation methods failed to produce valuable information that saved American lives. In Morocco, the government was targeting international terrorists as well as its own citizens, who had not necessarily been identified by the C.I.A. Mr. Jamai and others believe that the local authorities exploited the United States’ war against terrorism to intimidate the Moroccan opposition and independent press.

After he was tortured, Mr. Moumni was sent immediately to trial, where he was convicted on criminal fraud charges that Human Rights Watch and Amnesty International said were trumped up in retaliation for his criticism of the monarchy. He was sentenced to three years in prison and served 18 months before he was pardoned by the king to end a diplomatic feud with France — Mr. Moumni is also a French citizen. He has filed suit against the Moroccan officials he says authorized the torture. The Moroccan government denies the allegations and has filed a legal complaint in France to challenge them.

Several human rights organizations claim the Moroccan intelligence services used the Temara center heavily after a 2003 terrorist attack in Casablanca that killed 45 people. A Human Rights Watch report issued a year later said the authorities held people beyond legal time limits without contacting their families or lawyers.

When King Mohammed VI of Morocco succeeded his father in 1999, he promised to end human rights abuses and even spoke vaguely about democracy. A hallmark achievement in the king’s early years was establishing the Equity and Reconciliation Commission to prevent a return to the atrocities committed during his father’s reign.

Under the commission, people spoke out about their suffering and were compensated. But torturers were not prosecuted. In 2003, after the adoption of an antiterrorism law, human rights advocates sounded alarms about secret detentions, kangaroo courts and torture. They gained little traction as the United States prepared to invade Iraq.

“What we saw in Morocco is what we saw in the U.S.,” said Eric Goldstein, deputy director of the Middle East and North Africa division of Human Rights Watch. “After the attacks, security agencies were caught unprepared, they took the gloves off to interrogate massive numbers of people, and we saw a regression in both countries.”

During this period, Morocco was among Washington’s staunchest allies in the campaign against terrorism. “In the area of security cooperation, Morocco is one of our closest counterterrorism partners in the Middle East and North Africa region,” William Roebuck, then the deputy assistant secretary of state for Near Eastern affairs, said in testimony to Congress in April.

But the Senate’s report recounts how C.I.A. officers heard the cries of non-C.I.A. detainees tortured in Temara and complained to their Moroccan counterparts about the abuses. The report states that the relationship between the two sides deteriorated after the C.I.A. complained. American intelligence officials even contemplated building their own facilities in Morocco, but eventually gave up on the idea.

The Moroccan Interior Ministry, which oversees the intelligence services, did not respond to requests for comment.

The Moroccan authorities have denied that they tortured people. In 2011, protesters held rallies to ask for democratic changes. In May 2011, the pro-democracy February 20 Movement that led the protests, organized a picnic in front of the Temara center but was violently repressed by the authorities. An investigation was ordered, without much result.

“I visited the so-called secret detention center in Temara on May 18 to see what they say is a place where human rights violations and shameful violations of human dignity are practiced,” Moulay Al Hassan Al Daki, prosecutor general, said in 2011, “but all I found was administrative offices. I have not seen anywhere what could be considered a secret detention center or a place where people could be maltreated or abused.”

For Oussama Boutahar, who said he was detained in Temara twice — after 9/11 because he had fought with Islamic militants in Bosnia in the ’90s, and also in 2003 — the abuses were real.

“Everyone who was suspected to have any ties to terrorist groups went through Temara,” said Mr. Boutahar, 44, who is now an advocate against torture. “My torturers have told me that the Americans were pressuring Morocco to do this. America legitimized brutal treatments.”

Though most detainees were tortured as part of a larger campaign against terrorism, others with no ties to militancy also landed in Temara.

“If we want to stop torture, we must judge those responsible,” he said.

A version of this article appears in print on , on Page A6 of the New York edition with the headline: Morocco Crushed Dissent Using a U.S. Interrogation Site, Rights Advocates Say. Order Reprints | Today’s Paper | Subscribe