Cairo, Egypt (CNN) -- As some opposition groups met with the Egyptian government in an effort to find a diplomatic solution to its political crisis, reports continued to surface of security forces detaining journalists and human rights activists.
On Sunday, an Al-Jazeera English correspondent was detained by the military on Sunday, though Egyptian leaders insisted that journalists and others were free to carry out their work in Egypt. He was released later that night, Al-Jazeera said.
Al-Jazeera English's Cairo-based correspondent, Ayman Mohyeldin, was detained from early Sunday afternoon until night, network producer Tristan Redman told CNN. Another correspondent, Sherine Tadros, was held at a military checkpoint near the television station, but released within the hour, he said.
Mohyeldin was near Tahrir Square, the focal point of protests against the Egyptian government, when he was detained.
Egyptian Prime Minister Ahmed Shafiq told CNN that authorities have been told "not to bother" human rights activists and journalists working at anti-government protests.
If there have been such problems, they are "not intended," Shafiq told CNN's Candy Crowley. Arrests of journalists and human rights activists "are not allowed at all."
A U.S. embassy spokesperson in Cairo told CNN that the American government has raised the issue of the treatment of journalists with the Egyptian government "consistently, and will continue to do so."
Sameh Shoukry, Egypt's ambassador to the United States, also said the Egyptian government is opposed to violence against journalists of human rights workers.
"The government has denied its involvement in acts of violence and has promised a full and wide investigation that will be transparent and that will find those responsible," he said on NBC's "Meet the Press" Sunday.
All forms of violence have been condemned, he said.
Asked whether the government had ordered a crackdown on journalists, Shoukry said, "I think that whatever the case, we must resort to a full investigative process."
He said that such accusations were based on "assumptions" and not proof.
A leading international human rights group says military police raided the offices of Hisham Mubarak Law Center late last week and arrested some 35 journalists and human rights activists documenting the crisis in Egypt.
They were freed Friday after nearly two days in military custody, Amnesty International said.
"We welcome the news that these activists have been freed, but we are outraged that they were detained in the first place and by the manner in which they have been treated," said Malcolm Smart, Amnesty International's Middle East and North Africa director.
He said the whereabouts of several other activists detained in separate incidents are unknown.
"The Egyptian authorities must now carry out an urgent independent investigation into why human rights activists monitoring protests in Cairo were targeted in this way, and who gave the orders for it," Smart said.
In recent days, some have accused President Hosni Mubarak of orchestrating the assaults to suppress international coverage of bloodshed by pro-government operatives against peaceful protesters in Cairo's Tahrir Square.
Journalists attempting to cover unrest in Egypt also reported being beaten, arrested and harassed by security forces and police on Thursday, leading to sharply limited television coverage of the protests.
Along with Al-Jazeera, other news outlets -- including the BBC, Al-Arabiya, ABC News, the Washington Post, Fox News and CNN -- said members of their staffs had been attacked or otherwise targeted.
Besides Amnesty International, Human Rights Watch also reported that staffers were detained.
U.S. State Department officials told CNN earlier that they had information that Egypt's Interior Ministry was behind the journalist detentions, citing reports from the U.S. Embassy in Egypt.
CNN's Pierre Bairin and Ben Wedeman contributed to this report