An Iraqi demonstrator wears a mask with the Arabic word "Government" written on it during a protest against corruption, unemployment and poor public services in Baghdad on May 6, 2011. (AHMAD AL-RUBAYE/AFP/GETTY IMAGES)

Four Iraqi men who were apparently swept into an unmarked van during anti-government demonstrations last week are still being held, family members said Thursday. And their arrests have provoked more protests in Baghdad’s main square, including one on Friday.

For months, groups of students and activists have been gathering in Tahrir Square, demanding government reforms, jobs, more electricity and clean water. With often only a few hundred participants, the weekly demonstrations this spring have been far smaller and restrained than some in other Arab capitals.

But at the May 27 protest, according to demonstrators, several security officials tossed four young men into an “ambulance” that had pulled up beside them. The four, three of whom are college students, have been held since their arrest, and friends and parents say they have been unable to see them.

“They were walking before the demonstration started, and it was a strange ambulance because it was just white without the red lines,” said Mohammad Fenjan, 30, the brother-in-law of one of the men. “It was so clear it was a security unit inside because there was both guys in there with civilian and military uniforms inside.”

On Thursday, 13 protest organizers were released after soldiers in Humvees raided a gathering in Baghdad the day after the May 27 arrests, said Hana Edward, secretary of the al-Almal (Hope) organization. Some of the detainees said security officials took them to a military facility and beat them, a Human Rights Watch official said.

Concerned that the detentions are part of a broader effort by the Iraqi government to quash dissent, human rights officials have joined with student organizers to decry the incident. On Thursday, student leaders and the parents of some the young men held since May 27 called a news conference in Baghdad to blame the detentions on Prime Minister Nouri al-Maliki, who has kept firm control over Baghdad’s security forces.

“We have questions to the government, and they are: Where are our sons?” asked Alla Mudher, who has not seen her son Ahmad, since last week. “Who detained them? Why?

Spokesmen for al-Maliki and the Interior Ministry, which oversees Iraq’s national police, were not immediately available for comment. But security officials said earlier in the week that the men have been charged with carrying false identification.

Hanna Mohammed said government officials told her on May 27 that her son, Ali al-Jaff, was arrested for “insulting and libeling the prime minister.” The next day, however, Mohammed said authorities told her the charge was organizing an unauthorized demonstration. This week, she said, officials told her that Jaff was being held for carrying false identification.

Edward said she and family members went to the Ministry of Human Rights on Wednesday to plead for the men’s release. She said they were told the four were in “good health” but that family members would not be allowed to visit them until at least June 11.

At the protest on Friday, several hundred people gathered in Tahrir Square holding photographs of the detained men while chanting “peaceful” and “Maliki free the four.”

The protesters briefly attempted to surge onto the street surrounding square, but were quickly corralled by several dozen soldiers armed with assault weapons and batons nearly as long as their legs. There did not appear to be any arrests or violence.

But in a sign that democratic reforms in Iraq remain tenuous, an Iraqi soldier seized a flyer with photographs of the men from a Washington Post reporter who was trying to enter the square.

“You have no right to hold this slogan,” the soldier said.

Faisal al-Maliki, 60, said he came to the protest demand the release of what he suspects are hundreds of Iraqi citizens being detained for speaking out against the government – a claim that cannot be independently verified.

“Today, we came here to ask, in a peaceful way, without any kind of weapons, to set them free,” al-Maliki said.”There is no stone or rock in our hands, just pictures and we ask the government to set free all of the innocent people. ... There is no implementation of the law for them, they are still in jail.”

Haydir Ali, 25, said the demonstrations in Iraq are not generating the numbers of protesters they have in other Arab countries because “they want to change the regime” while protesters in Iraq are “trying to reform the regime.” But Ali expects even large demonstrations in the coming weeks if arrests and detentions continue.

“The government should be in charge of all people and the constitution said we have the right to practice our speech,” Ali said.

In February, following violent clashes between demonstrators and security forces nationwide that killed at least 23 people, Prime Minister al-Maliki gave his ministers 100 days to improve services. The action helped dampen anti-government protests in many smaller cities, but demonstrations continued in Tahrir Square and in Kurdistan. With the 100-day deadline approaching next week, some fear large protests could resume nationwide as early as June 10.

Joe Stork, deputy Middle East director at Human Rights Watch, said the arrests in Tahrir Square appear to be a government intimidation tactic against protest organizers in Baghdad and Kurdistan.

In Kurdistan, where several large demonstrations have pushed for more democratic reforms, an organizer was abducted, stabbed and beaten on May 27, Stork said.

“Authorities in Baghdad and in Iraq-Kurdistan are keeping citizens from demonstrating peacefully,” he said. “Iraq needs to make sure that security forces and pro-government gangs stop targeting protest organizers, activists and journalists.”