A High Court judge on Monday told the prosecution to amend the murder charge against two defendants over the death of a cleaner in Sheung Shui during the social unrest of 2019.

After considering the evidence presented by the prosecution, Judge Esther Toh said it wasn't enough to support a murder charge and ordered Chan Yi-ting and Kelvin Lau to be charged with manslaughter instead.

The court heard that the cleaner, 70, died in November 2019 after he was hit on the head by a brick in Sheung Shui as two groups of people clashed.

The two defendants, aged 18 and 19, also face two charges of wounding with intent and rioting each.

The trial continues on Tuesday.