Avril Lavigne backs ex-husband's band Nickelback, calls Zuckerberg a bully

Zuckerberg had joked earlier that the rock band did not have good songs

Singer Avril Lavigne has hit out at Facebook CEO Mark Zuckerberg for bullying her ex-husband Chad Kroeger-led rock band Nickelback.

The Canadian singer-songwriter responded to a video, wherein Zuckerberg makes a time-old joke about the rock band that they don't really have good songs.

The "Complicated" hitmaker, who separated from Kroegar last year, slammed Zuckerberg, saying his jab at Nickelback is in "poor taste".

Taking to Twitter, she said: "Many people use your products- some people love them and some people don't. Either way, you're allowed your musical opinion however, your jab at Nickelback is in poor taste."

In what appears to be a letter addressed to the Facebook founder, she wrote: "When you have a voice like yours, you may want to consider being more responsible with promoting bullying, especially given what's going on in the world today. Say No To Bullying. The Joke Is Old. Nickelback Has Sold Over 50 Million Albums."