Cammaert arrived in Hodeidah last month on top of a team to oversee the ceasefire and the troops redeployment agreed upon by Yemen’s government and the Houthi rebels at talks in Sweden earlier in December.
Speaking on condition of anonymity, the diplomats said UN will replace him by Michael Anker Lollesgaard, next month.
Lollesgaard had led the UN mission for peacekeeping in Mali in 2015-2016.
He will report to the UN special envoy to Yemen, Martin Griffiths.
He will take charge of increasing to monitoring mission to 75 persons, which was approved this month by the UN Security Council.
The reason behind Cammaert's resignation is still unclear.