Before this weekend, the names Rimba Hutani Mas, Sebangun Bumi Andalas, Bumi Sriwijaya Sentosa and Wachyuni Mandira would hardly have rung a bell with Singaporeans.
The National Environment Agency (NEA), however, changed that by connecting the companies to peatland fires in Indonesia detected on concession lands under their charge.
These illegal fires remain the source of the haze that has adversely affected millions of people, not just in Indonesia but also in Malaysia and Singapore .
While this may be the first time the four Indonesian firms have come under the scrutiny of the NEA, it is not their first brush with controversy for some of them.
Rimba Hutani Mas and Sebangun Bumi Andalas Wood Industries are both suppliers for Asia Pulp and Paper (APP), Indonesia's largest pulp and paper company.
APP is also the most established business entity among the companies which the NEA said it is investigating under the Transboundary Haze Pollution Act.
Rimba Hutani Mas, which is a unit of Indonesian conglomerate Sinar Mas, runs pulpwood concessions in the Musi Banyuasin regency in South Sumatra. It is reportedly under investigation by police in the province for illegal land-clearing practices.
Sebangun Bumi Andalas is also a Sinar Mas subsidiary. It operates pulpwood concessions in the Ogan Komering Ilir regency in South Sumatra. The Musi Banyuasin, Ogan Komering Ilir and Banyuasin regencies are three of the areas worst hit by peatland fires in Sumatra this year.
APP and its suppliers control concessions covering 2.6 million ha in Indonesia. There were more than 300 fire alerts recorded on those concessions in Sumatra earlier this month.
Bumi Sriwijaya Sentosa runs a sugar cane concession in Ogan Komering Ilir. It has been reported that the firm had land disputes with residents from 17 villages, who accused the firm of encroaching on to land owned by farmers.
Wachyuni Mandira is a shrimp- farming company that is also based in Ogan Komering Ilir. The firm was granted 30,000ha of land for non-forestry purposes. This means it cannot cultivate pulpwood trees, for instance.
The owners of Bumi Sriwijaya Sentosa and Wachyuni Mandira could not be traced, but they have no known ties to any of the major conglomerates in Indonesia.