UNITED NATIONS (Reuters) - United Nations Secretary-General Ban Ki-moon deplored on Monday an Arab coalition airstrike in Yemen that seriously damaged a UN Development Programme office and injured a guard, calling for a full investigation into the incident .

Ban's spokesman Farhan Haq said the airstrike happened in the southern city of Aden on Sunday.

"The Secretary-General strongly believes that this incident only underscores the imperative that all the parties to the conflict must end the fighting and return to the negotiation table as the only possible way to achieve a durable peace in Yemen," Haq told reporters.

(Reporting by Michelle Nichols; Editing by Meredith Mazzilli)