WASHINGTON — One of the nation's largest public-sector unions is severing its ties with the United Negro College Fund because the group accepted donations from the Koch brothers and its president spoke at a Koch-funded summit.

In a letter sent Tuesday, AFSCME President Lee Saunders wrote that the UNCF has taken actions "deeply hostile" to public employees, which he considers a "profound betrayal of the ideals of the civil rights movement," and that the union will end its relationship with UNCF.

Saunders cited the UNCF's decision to accept a $25 million grant from Koch Industries, Inc. and the Charles Koch Foundation as a reason for the split, as well as the decision by UNCF President Michael Lomax to speak at a summit hosted by the Kochs in California.

The Kochs have donated tremendous amounts of money to advance conservative political causes in recent years, as well as well as various philanthropic efforts.