Indonesia's state-owned asset management company PT Danantara Sumber Daya Indonesia (DSI) plans to impose a margin fee on exports of coal, palm oil and ferroalloys, as the government seeks to capture more value from the country's natural resources.

DSI is still calculating the level of the fee and has said it will seek only a "reasonable" margin to recover the costs of its operations, rather than impose an additional export tax, according to company officials cited by CNBC Indonesia.

The planned fee comes as DSI expands its role in monitoring Indonesia's commodity exports under a new single-gate system aimed at preventing under-invoicing, improving transparency and ensuring that more export earnings remain within the country.

DSI Finance and Treasury Director Sinthya Roesly said the company needed to recover the costs incurred in carrying out its export-monitoring and intermediary functions because it operates as a capitalized state-owned company and cannot run at a sustained loss.

DSI has also stressed that the margin should not represent excessive profit and would be linked to the services and intermediary role provided by the state-owned company.

Higher costs could initially be absorbed by exporters through lower margins. However, if the market remains tight or international prices rise, some of the cost could eventually be passed through to overseas buyers.

China is one of Indonesia's largest coal customers, while Indonesian coal is also an important source of supply for India and other Asian markets. Any increase in transaction costs could make Indonesian coal marginally less competitive against domestic coal in China.