Singapore has lodged a protest with Indonesia over a spike in hotspots just weeks after air quality in the island-nation returned to safe levels.

Tensions between the two countries have just simmered down after smoke, triggered by Indonesian forest fires, engulfed Singapore in hazardous haze when hotspots were detected in Sumatra Island over the weekend.

According to Singapore’s National Environment Agency, satellite imagery showed a marked increase in the number of hotspots in Sumatra, with 261 on Sunday and 252 on Monday.

Ronnie Tay, the chief executive of NEA, said it has registered a complaint with Indonesia on Monday.

Singapore would “once again be shrouded by smoke haze if the hotspots in Sumatra continue to remain high,” Tay said in a statement.

In a letter to Arief Yuwono, the Indonesian Deputy Minister for Environmental Degradation Control & Climate Change, Tay said Singapore could help with early detection of hotspots and deploy aircraft in cloud seeding to induce rain, reports the Wall Street Journal.

Indonesian authorities said there has been new sporadic burning of forests – a quick and cheap way to clear land for palm oil plantations – but said Jakarta is working to douse the fires.

Last month, smoke from forest fires in Sumatra sent Singapore’s air pollution index to peak at 401, the worst recorded haze.

Southeast Asian nations urged Indonesia to sign a pact aimed at tackling the haze problem.