The Arab Organisation for Human Rights (AOHR) in Syria said on Tuesday that US forces have prevented the 288 truck drivers from returning home for more than a week.
Witnesses said the hauliers are being held in Rabiaa near the Iraqi-Syrian border.
Muhammad Radun, head of the Syrian branch of the AOHR, told Aljazeera.net the case was brought to his attention by the drivers.
"All these drivers have done is drop goods off in Iraq and they now want to make their way back home, but they are being prevented by US forces," he said.
Radun thinks the drivers are being held back because US forces hold the drivers responsible for a series of recent explosions in the Rabiaa area in west Iraq.
He said: "We suspect the US troops are keeping the drivers in Iraq in connection to the attacks. They are now interrogating the drivers but they are not responsible for the attacks."
The US military was unavailable to comment.
One of the drivers, Jihad Sadiq, said: "An explosion rocked a police centre only 50m away from us. We are in a dangerous zone, between the Americans and Iraqi police.
"We have been held in the chilly weather for seven days. We have nothing anymore; no money, water or food. We don't know what to do
"We have families and children waiting for us.
"Whenever we talk to the Iraqis, they say speak with the Americans. When we talk to the Americans, they say speak to the Iraqis. No one is answering us"
a driver held by US forces
"They gave no reasons behind our capture. Whenever we talk to the Iraqis, they say speak with the Americans. When we talk to the Americans, they say speak to the Iraqis. No one is answering us."
AOHR's Radun said he believed the stalemate was a matter of diplomacy.
"The Syrian government has done nothing to help the situation because they do not want to antagonise the Iraqi government," he said.
"All we want to do now is bring the situation to the attention of other human rights groups across the world and receive their backing as our own government is not helping us."