The memorial to a victim of a racist murder in Norway has been vandalised, just days before the country commemorates victims of far-right attacks in 2011.

       Police in Oslo have launched an investigation after a statue of Benjamin Hermansen was damaged.

       Hermansen, a Norwegian-Ghanaian boy, was murdered by three members of the neo-Nazi group in a racially motivated attack in 2001.

       A memorial to the 15-year-old in Holmlia, near the capital city Oslo, was tagged with the words "Breivik was right", a reference to the perpetrator of the 2011 attacks.

       On Thursday, Norway will pay tribute to the 77 victims who died when Anders Behring Breivik committed a bomb attack in the Norwegian capital and mass shooting at an AUF youth camp on Ut？ya island.

       A decade on from Breivik's killing rampage, Norway still needs to address its far-right problem

       The vandalism on the statue of Hermansen was discovered on Tuesday by Johannes Dvorak Lagos while on a walk near his home.

       Lagos posted an image of the graffiti on Twitter, describing it as a "reprehensible" act.

       The damage has also been condemned by Norway's Prime Minister Erna Solberg and opposition Labour leader Jonas Gahr St？re.

       "It is absolutely awful to see that the Benjamin Hermansen memorial at Holmlia has been tagged down just before 22 July," Solberg said on Twitter.

       "I am sad and furious, and this shows how important it is that we stand up against racism and hate speech every single day."

       "It's reprehensible and it shows that dangerous attitudes are still circulating," St？re added on Twitter.

       "The police must take it seriously, and together we must speak out against this."

       Authorities say they are investigating the matter as a potential hate crime and added that the graffiti had been removed on Tuesday afternoon.

       Meanwhile, Norwegian police also arrested three men on Tuesday as part of an ongoing investigation into right-wing extremism.

       Authorities detained one man and seized dozens of weapons during a raid in Bod？, while two others from Lillestr？m and Hamar were also arrested.