The number increased from 150 hotspots on the previous day, according to the Pekanbaru meteorology office.
Based on monitoring by Terra and Aqua satellites, 77 hotspots were found in South Sumatra, 33 each in Lampung and Bengkulu, 14 in Bangka Belitung, nine in Riau, four in West Sumatra, three in Jambi, and one on Riau Island.
In Riau, four hotspots were found in Indragiri Hulu District, two in Rokan Hilir, and one each in Bengkalis, Pelalawan, and Meranti Island.
Riau remained prone to forest and plantation fires due to prevailing drought, Ardhitama, an analyst of the Riau meteorology, climatology and geophysics office, remarked.
Brigadier General Sonny Aprianto, commander of the Riau forest fire task force, had earlier ordered to take firm action against arsonists.
He also gave shoot-at-sight orders to his officers for perpetrators of forest and plantation fires.
The commander believed that 99 percent of the forest and plantation fires in Sumatra were induced by human activities.
By imposing legal enforcement and firm control, the Indonesian government has managed to reduce forest fires by 96.5 percent across the country during the 2015-2017 period.
Based on data obtained from NOAA`s satellites, 21,929 hotspots were found across Indonesia in 2015, and the figure dropped to 3,915 in 2016, and again 2,257 in 2017, according to Raffles B. Panjaitan, director of forest and plantation fire control of the environmental affairs and forestry ministry.
The wild fires had razed a total of 2,611,411 hectares in 2015, and the figure decreased to 438,360 hectares in 2016, and again to 165,464 hectares in 2017.
"Since 2016, companies have no longer dared to open new plantation land by setting fire, and only a small number of hotspots remain due to negligence," he added.
Reporting by FB Anggoro and Muhammad Said