The United Nations itself and it's two main constituent mechanisms, the General Assembly and Security Council would be like you said an intergovernmental organisation. The International Labour Organisation is an agency of the UN (essentially it gets all of its funding from the United Nations) but runs quite independently to the intergovernmental aspects of the General Assembly. A director is appointed, that is currently Gus Ryder and acts quite autonomously from the rest of the UN and UN member nation states. It has its own budget, hiring practices and decides what programs it runs. As a result, even though it is loosely connected to the United Nations through its funding model, the International Labour Organisation itself, as an organisation would be classed as an NGO. You could make a similar argument for other UN agencies such as the UN World Food Programme, the World Bank, ICAO (International Civil Aviation Organisation), the IMF (International Monetary Fund) etc. Hope that helps!