We will have to refer this matter to the relevant authorities.

refer 是动词，意思是"提交、转交、提及"，常与介词 to 搭配使用。 to 在这里是介词，表示动作的方向或对象，与 refer 搭配构成短语 refer to，意思是"提交给..."或"转交给..."。 refer to 这个短语表示"将某事提交给某人或某机构处理"。