Singapore and Indonesia are to hold an emergency meeting on Thursday, June 20 after haze in Singapore soared to hazardous levels, BBC News reports.

Singapore's environment minister said his team would "insist on definitive action" from neighboring Indonesia.

Late on Wednesday Singapore's pollution standards index (PSI) hit 321, breaking all previous records and prompting government health warnings. The haze is caused by illegal forest fires in Indonesia's Sumatra island.

Andrew Tan, the chief executive of Singapore's National Environment Agency, will lead Singapore's delegation at the emergency meeting, hosted by Indonesia's foreign ministry in Jakarta.

Dr Vivian Balakrishnan, Singapore's Environment and Water Resources Minister, wrote on his Facebook wall that "Singaporeans have lost patience, and are understandably angry."

"No country or corporation has the right to pollute the air at the expense of Singaporeans' health and wellbeing," he added.

Singapore's buildings have been obscured by the polluted air and the smell of burnt wood has permeated the city-state.

Prime Minister Lee Hsieng Loong has asked Singaporeans to "stay indoors where possible and avoid heavy outdoor activities". The military has also reportedly suspended all outdoor training.

The poor air quality has prompted widespread buying of disposable face masks, leading shops to run out of stock. A PSI reading above 200 indicates "very unhealthy" air, while a PSI score above 300 is "hazardous".

Air quality in parts of Malaysia has also reportedly deteriorated, with some areas badly affected by the smog.

Indonesia's forestry ministry said it intended to use cloud seeding to try to induce rain on Sumatra. The fires are started to clear land for plantations.

Indonesian officials have suggested that foreign palm oil investors, including Singaporean companies, may bear some responsibility for the fires. However, several major Singapore-based palm oil companies have denied any involvement.