The number of vessels banned by the Paris MoU port state control group jumped to 20 last year.
This compares to 11 in 2015, it said.
Detention percentages are also rising, from 3.4% to 3.8% over the same period.
The number of detainable deficiencies has increased 7.3% compared to 2015, from 17,840 inspections, slightly less than the 17,877 carried out in 2015.
