Police media spokesman SSP Ajith Rohana confirmed that the driver had been detained but refuted claims that the occupants of the van were also arrested.
He said the driver was arrested after ganja was found in his possession and investigations were now underway.
However the Jaffna media reported that the ganja had been planted in the van by a soldier who was with the police at the time the van was checked at Omanthai.
The Jaffna media reported that the journalists were heading to Colombo to attend a workshop when their vehicle was stopped at Omanthai by the police.
On finding the ganja the police took the driver and journalists to the police station but later released the journalists