A CREW of 19 Syrian sailors were given permission to leave their ship despite only one having a valid visa as they approached Gladstone.
The revelations have frustrated the International Transport Workers' Federation, which is calling for greater scrutiny of foreign ships in Australian ports.
The crew of the 35,000-tonne Lebanese tanker "OS 35" docked in Gladstone on July 10.
Foreign seafarers are expected to be cleared by security checks to be approved for a Maritime Crew Visa or MCV ahead of their arrival.
Security checks imposed on foreign sailors are far less rigorous than those applied to Australian crews.
The Department of Border Protection confirmed 18 of the 19 sailors on the OS 35 did not have proper clearance when discovered by Australian Border Force officers off the Queensland coast.
But according to the department, officers were "able to assess and process the group ahead of their arrival and all were granted MCVs by the time they anchored at Gladstone".
All of the 18 passed their rushed security checks, according to the department.
"Australian Border Force did not place any restrictions on the crew. The crew passports were inspected and returned to the ship," a spokesman said.
Once visas are approved, seafarers have the right to shore leave under international law.
ITF coordinator Dean Summers said the government's lax approach to these visas put Australia's borders at risk.
"Are ships whose entire crew do not have MCVs allowed to come alongside Australian ports?" he said.
"Is trade more important than national security?"
Mr Summers said the only way this ship's crew could have undergone a proper security check was if Australian officials were able to check information with their home country of Syria.
"I think the Syrian Government's hands are pretty full at the moment, and they don't have a relationship with the Australian Government."
The current Syrian Government is involved in a bloody conflict which has cost more than 100,000 lives.
A spokesman for the the department said officials may liaise with foreign governments when assessing visa applications.
He would not discuss this case specifically.
The Department of Border Protection and Australian Border Force have been under scrutiny since earlier this year when a Filipino ship captain, wanted for questioning in relation to two deaths aboard his former vessel, was given permission to work in Australian waters.
Captain Venancio Salas Jr was found to be in Gladstone in February following a major investigation by Australian Regional Media . He was then forced to face cross-examination at a coronial inquest.
The handling of the case has now become the subject of a Senate Inquiry into foreign shipping.
NOTE: The initial headline on this story was "19 Syrian sailors allowed into Gladstone without visas", which was inaccurate and has been changed.
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