Secretary-General Ban Ki-moon has been briefed on the latest developments in Haiti.
He has expressed shock at the scale of the devastation in Port-au-Prince, at the headquarters of the UN Stabilization Mission in Haiti and at other UN buildings.
A UN spokesman says the Secretary-General is anxiously awaiting further news about missing UN staff and about the people of Haiti.
Former US President Bill Clinton, the Secretary-General's Special Envoy for Haiti, called the Secretary-General to discuss the unfolding disaster. They exchanged initial information and agreed to talk again on Wednesday morning.
The Secretary-General also spoke by phone with Ambassador Susan Rice, the Permanent Representative of the United States to the United Nations.
They agreed to closely coordinate rescue and assistance efforts with other international partners.
The Secretary-General has been receiving regular updates from his senior advisers on developments and on the humanitarian relief response.
Meanwhile, Under-Secretary-General for Peacekeeping Operations, Alain Leroy has expresses his deep concern following this afternoon's catastrophic earthquake.
The Department of Peacekeeping Operations is still in the process of gathering information on the extent of the damage and the status of UN personnel.
Contacts with the UN on the ground have been severely hampered as communications networks in Haiti have been disabled by the earth quake.
For the moment, a large number of personnel remain unaccounted for.
The United Nations can confirm that the Headquarters of the UN Stabilization Mission in Port au Prince has sustained serious damage along with other UN installations.
This is Donn Bobb reporting for United Nations Radio