"We will do everything we can," Foreign and Law Minister K Shanmugam said today, adding Singapore would offer "no succour nor refuge" to the companies found guilty.
He said there were limits in international commercial law to what Singapore can do about companies operating outside the country, but the Attorney General has been asked to look into this.
Meanwhile, the Indonesian government has also started investigating eight companies for allegedly causing fires that has led to thick haze in Singapore and Malaysia.
Some of these companies were linked to major corporations based in Singapore and Malaysia.
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Singapore environment minister Vivian Balakrishnan visited Jakarta yesterday and met his Indonesian counterpart, Balthasar Kambuaya, for talks on the fires and haze.
"We have got to join the dots and get the train of accountability back to the companies and the stakeholders who are responsible for this disaster," Balakrishnan said.
Lee also offered Singapore's help to put out the fires, including an aircraft for cloud seeding and satellite pictures and hotpot coordinates to identify the culprits behind them, according to local media reports today.
Indonesian authorities yesterday declared a state of emergency in Riau province on Sumatra, the epicenter of forest fires, reported The Jakarta Post today.
The Pollutant Standards Index (PSI) hit a high of 401 yesterday afternoon in Singapore and has remained in the range of 200-300 since then.