Thousands of people are expected to attend a Black Lives Matter rally outside the State Library of Victoria at midday.

More than 8000 have expressed interest on the Facebook page for the rally, organised after a spate of police shootings of African Americans.

Police say they will be well resourced and prepared to act if the rally turns violent.

Organisers say the rally will be a display of solidarity with the US movement, but will also highlight Indigenous Australian deaths in custody that are "taking place on our own soil".

Organisers have told people to wear black and "bring a peaceful mindset".

"No violence and no weapons," the Facebook page says.

Yarra Trams has warned of possible disruptions to service during the rally.

The Melbourne rally follows a similar event in Sydney on Saturday.

The rally comes after the shooting death of two US men, Alton Sterling and Philando Castile, at the hands of police.

Five police officers were also shot and killed at a Black Lives Matter protest in Dallas, Texas.

More to come