The Arabic TV network al-Jazeera has accused US-led forces in Iraq of harassment, after one of its journalists was detained this week.
Al-Jazeera denies being in league with anti-US guerrillas
Cameraman Samer Hamza was freed on Wednesday after two days in custody.
Al-Jazeera's editor told BBC News Online that this and other incidents suggest his organisation is being deliberately targeted by US troops.
And the advocacy group Reporters Sans Frontieres urged US forces to do more to respect journalists working in Iraq.
Mr Hamza and his driver were picked up by US-forces on Monday in Baghdad, at the scene of the attack on a police station.
The blast was one of a series of attacks that killed 36 people and injured more than 200.
Al-Jazeera editor-in-chief Ibrahim Helal accused the US troops of singling out his colleagues.
"We have had more than 15 arrests in recent months in Iraq," he said on Thursday. "It has become systematic."
On 3 October another al-Jazeera journalist, Salah Husein Nussaif, was arrested by Iraqi police in Shahraban, 100 kilometres (60 miles) from Baghdad, and spent three days in the custody of both Iraqi and US forces.
Mr Helal said coalition soldiers were under "unwritten orders" to detain al-Jazeera reporters, whom they suspect of having links with anti-US guerrillas.
Every time we cover an attack, the accusation is always - how did you know about the attack? How did you arrive so quickly?"
Cameraman Mazen Dana was killed in August
But Mr Helal denied that his organisation had advance notice of any attack.
"We have never been to any scene before the other journalists," he said.
Al-Jazeera was targeted because US forces regarded the Qatar-based channel a sympathetic to opponents of the US-led coalition.
But Mr Helal denied this, saying his staff had also been attacked by Shia radicals.
US military authorities in Iraq have declined to comment.
The Paris-based organisation Reporters Sans Frontieres (RSF) said the two al-Jazeera journalists were not the only ones detained by US forces in Iraq in October.
Patrick Baz, a photographer with AFP news agency, told RSF that he and a colleague from Reuters were briefly arrested in Falluja after an attack on a US convoy there on 19 October.
"The soldiers on the ground are in a hostile environment, and the mission of journalists has not been properly explained to them," RSF spokeswoman Severine Cazes-Tschann told BBC News Online.
As a result some US troops have an aggressive attitude towards reporters, said Ms Cazes-Tschann - who visited Iraq in July.
She said the aim of the arrest of TV crews was two-fold - to gather information and delay the broadcasting of pictures of coalition forces that had been attacked.
"Whatever the pressure US forces are under, there can be no excuse," Ms Cazes-Tschann said. "Soldiers must be given instructions to respect the press."
She also condemned the fact that the US soldiers who killed Reuters cameraman Mazen Dana in August in Baghdad had been cleared.
The soldiers shot him dead after mistaking his camera for a rocket-propelled grenade launcher.
In September the Pentagon said that although this was "a regrettable incident" the soldiers acted "within the rules of engagement".