Authorities in the UK have seen a rise in the number of migrants using "clandestine" methods like containers and refrigerated trucks to illegally enter the UK over the last 12 months.
"The past year has seen increasing use of higher-risk methods of clandestine entry," the UK's National Crime Agency said in its latest report on Serious and Organised Crime.
"These include the movement of migrants (including children) into the UK in containers, refrigerated HGVs [heavy goods vehicle] and small boats, at a high risk to life of those migrants smuggled."
The report acknowledged that the extent of modern slavery and human trafficking in the UK was not truly understood. But it did say that the potential victims identified through the National Referral Mechanism -- a process to support and track data about victims -- had increased by 36%, between 2017 and 2018.