Ambalat is a block located in the Celebes Sea which is currently disputable between Indonesia and Malaysia. Ambalat block is located off the coast of East Kalimantan / Borneo (one of the Indonesian province) and south-east of the Malaysian state of Sabah. Malaysia refers to part of the Ambalat block as Block ND 6 while part of the East Ambalat Block is referred to as Block ND 7. These sea blocks are rich in crude oil and natural resources.
The Indonesia-Malaysia dispute over the Ambalat Block stretch of the Celebes Sea began with the publication of a map by Malaysia Government in 1979 showing its territorial waters and continental shelf.
This map drew Malaysia's maritime boundary running in a southeast direction in the Celebes Sea from the eastmost point of the Indonesia-Malaysia land border on the eastern shore of Sebatik island, thus including the Ambalat blocks, or at least a large portion of it, within Malaysian territorial waters. Indonesia, like the other neighbouring countries of Malaysia, has protested to the map.
Indonesia on the other hand, has never officially announced the exact locations of its maritime territorial limits. Indonesia declared the islands of Sipadan and Ligitan, which both it and Malaysia once claimed and which Malaysia included as part of its territory in its 1979 map, to be its archipelagic basepoints in June 2002.
This effectively put the entire Ambalat area within its internal waters. During the International Court of Justice case over the sovereignty of Sipadan and Ligitan, Indonesia argued that the Indonesia-Malaysia maritime boundary continued as a straight line along the 4° 10' North after it left the eastern land boundary terminus on the eastern shore of Sebatik Island. This would also have put the entire Ambalat Block Indonesian territorial waters.