JAKARTA, Nov 16 (Reuters) - Coal miner PT Indika Energy (INDY.JK) and Taiwan-based Foxconn (2317.TW), which are partnering to make electric vehicles in Indonesia, are considering bringing in a Thai firm as a third partner, Indika's top executive told Reuters on Wednesday.Arsjad said the venture would likely focus on manufacturing electric buses in its initial production and may later move to make electric trucks.Foxconn, Apple's biggest iPhone maker, also has a $1 billion joint venture with Thai energy group PTT (PTT.BK) to produce battery EVs.Indika has recently acquired local metal firm PT Perkasa Investama Mineral, which has a bauxite mining business, to secure materials for battery production, Arsjad said, adding that it is looking to buy other bauxite or nickel mines.Like many other energy companies, Indika wants to diversify its business to reduce exposure to coal - the most polluting fossil fuel - to reach a target of carbon neutrality by 2050."