The singer-turned-TV presenter discovered on Monday that direct messages (DMs) were being sent from her account without her permission, reported OK! magazine.
"If you're receiving DMs from me, I've been hacked by someone hilarious. Ignore guys," she wrote on her page.
Klass, 34, is the latest celebrity to have her page compromised in recent weeks. Eva Longoria, rockers Garbage, Rita Ora and Kristen Bell have also been targeted by hackers.