Fires illegally started to clear land for plantations on Indonesia's Sumatra island and the Indonesian part of Borneo have for weeks belched out thick haze, cloaking Singapore and Malaysia and prompting the cancellation of outdoor events and school closures.

The blazes are an annual occurrence during the dry season, but scientists have warned this year's could be the worst on record due to an El Nino weather system that has created tinder-dry conditions in Indonesia.

The drone footage filmed by Greenpeace showed acrid haze rising from dense jungle next to a national park, trees reduced to fire-blackened skeletons, burnt peatland and a city shrouded in smog on the Indonesian part of Borneo.

"Companies destroying forests and draining peatland have made Indonesia?s landscape into a huge carbon bomb, and the drought has given it a thousand fuses," said Bustar Maitar, Indonesian forest project leader for Greenpeace Southeast Asia.

"The Indonesian government can no longer turn a blind eye to this destruction when half of Asia is living with the consequences."

Pressure mounted in Singapore, where air quality has been unhealthy for weeks. Supermarket chain NTUC FairPrice, which belongs to a state-linked trades union, announced the withdrawal of all paper products sourced from Indonesian-owned Asia Pulp & Paper (APP), which has corporate offices in Singapore.

The company's suppliers are suspected of starting forest fires in Indonesia.

Singapore environmental and consumer groups asked home furnishings giant IKEA and retailers 7-Eleven and Watsons to certify that products they sell are not sourced from companies accused of causing fires in Indonesia.

Sandra Keasberry, a spokeswoman for IKEA Singapore, said the company "has not made any purchases from the companies named in relation to the burning practices leading to the haze".

- Mounting pressure -

Aida Greenbury, APP?s Jakarta-based managing director for sustainability, told AFP the company was working with the Indonesian military to fight forest fires on suppliers' landholdings, where more than 10,000 hectares (24,000 acres) had been affected.

"If any suppliers are found to have intentionally burned land, we will disengage with them," she said in a statement. "We are ready to step up and do more to address challenges in the landscape."

Tensions have been rising between the governments of Singapore and Indonesia over the haze. Singapore's Ministry of Foreign Affairs asked Indonesia in a statement Wednesday for an "early response" to its requests for information on "errant companies suspected of being involved in the haze".

APP was asked by Singapore's National Environment Agency last month to supply information on its subsidiaries operating in Singapore and Indonesia, as well as measures taken by its suppliers to put out fires.

The company said Wednesday it had provided information in response to the request.

Under a 2014 law Singapore can impose a fine of Sg$100,000 ($70,000) for each day that a local or foreign company contributes to unhealthy levels of haze pollution in Singapore, subject to a maximum total of Sg$2.0 million.