A young man provided entertainment for commuters as he climbed the Supreme Court building in Wellington tonight.

A witness said the man, who appeared to be in his 20s, climbed about 15m up the decorative metal lattice work covering the building on the corner of Lambton Quay and Bowen Street.

Police said they believed he was protesting but the witness said that was not apparent.

Police were not letting people walk directly under the man but the roads remained open.