Rock band U2 have lashed out at mindless violence (Sunday Bloody Sunday) and personal demons (One), among other issues, in their songs.

On Sunday (Dec 8), in their concert in Seoul, they also took a stand against cyber bullies.

When they performed Ultraviolet (Light My Way), photos of women, who had made headlines in South Korea, were shown on screens.

The women honoured included prosecutor Seo Ji-hyun, who brought attention to the country's Me Too movement, and singer Sulli, reported the Soompi portal.

A message - "Until we are all equal, none of us is equal" - also appeared on the screens.

Sulli, 25, who was found dead in October at her home, was reportedly hounded by netizens over her romantic life.

Recently, another singer, Goo Hara, 28, was also found dead at home.

Their deaths have sparked calls for more to be done for mental health and heavier punishment for abusive netizens.

On Monday (Dec 9), U2 singer Bono is slated to meet President Moon Jae-in to share views on global issues, including efforts to promote peace in the Korean Peninsula.

North Korea recently announced missile tests.