Leaders of the International Organization for Migration say they've unanimously agreed to become part of the U.N. system.

The 65-year-old intergovernmental body also announced Thursday that China, Tuvalu and Solomon Islands will join the IOM, bringing its total number of member states to 165.

The move by an IOM council to join the United Nations system, like other affiliate bodies such as the World Trade Organization, hands the issue over to the U.N. General Assembly.

IOM Director-General William? Lacy Swing called the move a "watershed moment" for the organization at a time when it counts one in seven people worldwide as a migrant.

IOM expects to now expand partnerships, but it made no reference to how it will articulate its work alongside that of the U.N. refugee agency, UNHCR.