The latest attack by suspected armed herder militias hit several farming communities on Sunday in Plateau's Barkin Ladi district, Plateau police spokesman Alfred Alabo told AFP late on Monday.
"In Barkin Ladi, we got reports that about 15 people lost their lives yesterday, and today another five have been buried, which make the total number to be 20," he said.
Plateau State sits on the dividing line between Nigeria's mostly Muslim north and predominately Christian south and has seen a recent surge in intercommunal clashes.
Plateau often sees surges in intercommunal tensions and tit-for-tat attacks between Muslim Fulani herders and mostly Christian farming communities, especially in Mangu, Barkin Ladi and Riyom districts.
Plateau State Governor Caleb Manasseh Mutfwang issued a condemnation, calling for the security forces to end "the wanton spilling of blood and burning of property."
On Friday, five herders were killed as they took cattle to market by suspected youths from a Berom farming community, a herdsman representative said.
Eight farmers were then killed in an apparent revenge attack, according to a Berom community leader.
Police later confirmed those attacks had left 13 dead.
Nigeria's northwestern and central states have seen a steady rise in clashes over land use and water between herders and farming communities.
The spiral has also fueled more general criminality as heavily armed gangs target villages for mass kidnappings, looting and killing.
Since mid-May, at least 140 people have been killed in communal clashes in Plateau and more than 3,000 people displaced.
The local authorities have deployed police in several districts in a bid to restore peace.