Published Wednesday, 04 July 2012
Belfast Port is one of four entry points to NI the task force monitors. (© Belfast Harbour Commission)
Almost 300 people were intercepted last year attempting to use the ports, according to the Organised Crime Task Force (OCTF) annual report.
The border agency's operation focused on two airports and two seaports - Belfast International and George Best Belfast City airports as well as the ports at Belfast and Larne.
The investigation targeted passengers between Northern Ireland and the rest of the UK.
According to the report, detection of illegal immigrants increased by around 60% overall in the last year, with 281 people intercepted attempting to abuse or help abuse the region's sea ports to illegally travel across the UK.
More than 70% of these offenders were removed from the jurisdiction.
A UK Border Agency spokesperson said: "Changes to the way enforcement is organised to target immigration offenders passing through ferry ports has seen an increase in the number of illegal immigrants detected at Scottish and Northern Ireland sea ports.
"Our enforcement team in Northern Ireland is becoming increasingly effective in dealing with this problem adding to the success they already have at airports and they are continuing to work closely with police to catch more illegal immigrants."
The agency's Operation Gull conducts periodic document checks at Northern Ireland's air and sea ports to intercept illegal migrants travelling between Northern Ireland and the rest of the UK.
In the six years since its introduction, more than 3,500 immigration offenders have been detected, with more than 60% removed from the UK.
Close working with the PSNI has resulted in more than 250 prosecutions and resulted in the seizure of more than £250,000 under the Proceeds of Crime Act over the last two years.
In the last year, the agency has increased its enforcement presence in Northern Ireland and has built a short term holding facility at Larne.