Numerous residents are still missing.
A spokesman for the government of the Herzegovina-Neretva canton had spoken of 14 fatalities earlier.
The mountainous region about 30km north of the city of Mostar, in the south of the country, is the worst affected.
Local media reported that heavy rainfall caused several rivers in the region to burst their banks.
According to the reports, a mudslide hit the town of Jablanica, damaging many houses and leaving only the town's mosque still visible.
In Jablanica alone, 16 dead were recovered.
The town was completely isolated, as the country roads nearby were unusable and the rain had washed away the earth beneath the railway tracks.
Rescue workers were eventually able to reach Jablanica and brought people to safety using boats, local media reported.
"I can't remember such a crisis since the war. The extent of this chaotic situation is shocking," the canton government spokesman said, referring to the Bosnian war from 1992-95.
He said that the situation remained serious, with bad weather forecast for the weekend.
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