A US-funded Iraqi television station has aired what it says are confessions by Iraqi insurgents who claim to have been backed by Syrian intelligence.
Syria is accused of supporting the insurgency in Iraq
Appearing on al-Iraqiya TV, the men say they were trained and financed by Syrian intelligence. The claims could not be independently verified.
The US accuses Syria of sheltering Saddam Hussein loyalists and allowing insurgents to cross borders.
Pressure has also mounted on Syria over an assassination in Beirut last week.
While the US has stopped short of blaming Syria for the bomb attack which killed Lebanon's former prime minister Rafik Hariri, calls have intensified for Damascus to pull its troops out of Lebanon.
The allegations made by the apparent rebels on al-Iraqiya TV would, if verified, back US and Iraqi claims of Syrian meddling in Iraq's affairs.
A man who was identified as Syrian intelligence officer Lt Anas Ahmed al-Essa said he and his group had been recruited to "cause chaos in Iraq... to bar America from reaching Syria," the Associated Press reported.
"We received all the instructions from Syrian intelligence," he said in the video broadcast.
He claimed he infiltrated Iraq two years before the US-led invasion, because Syrian intelligence were convinced the US would invade.
Reuters news agency quoted another group as saying they were trained in beheadings, bombings and shootings in the Syrian city of Latakia in 2001 in anticipation of a US invasion of Iraq.
Syria has not commented on the allegations, which were broadcast nationwide across Iraq.
Damascus has denied supporting the Iraqi insurgency, and says it has attempted to tighten its borders to prevent infiltration by rebel groups.
It has also strongly denied any involvement in the massive bomb attack earlier this month that killed Mr Hariri.
But tensions remain.
President George Bush recently laid out a list of demands he says he expects Damascus to meet.
They include ensuring Syrian territory is not used by former Iraqi Baathists or international terrorist groups, and to remove its troops from Lebanon.