NEW YORK (REUTERS) - The man accused of killing 10 Black people at a western New York grocery store pleaded not guilty to 27 hate crime and firearms charges stemming from the Buffalo shooting massacre, a court spokesperson said on Monday (July 18).

The accused gunman, Payton Gendron, 19, appeared briefly in the Buffalo courtroom of US Magistrate Judge Kenneth Schroeder Monday morning. He is charged with 14 hate crimes violations and 13 firearms offences.

Prosecutors have 45 days to turn over discovery to the defendant's attorneys, Barbara Burns, a US Department of Justice public information officer, told Reuters.

Gendron is due for a Dec 9 status hearing, Burns said. Gendron, who was 18 at the time of the mass shooting, is currently in state custody facing 10 counts of first-degree murder and 10 counts of second-degree murder in state court.

The Conklin, New York, man could face life in prison or the death penalty if convicted on the federal charges. Prosecutors must notify the court prior to trial whether they will seek a death sentence.

Authorities say the suspect, who broadcast the attack in real time to the livestreaming service Twitch, is a white supremacist who targeted the grocery store because it was the hub of a tight-knit, predominantly African-American neighborhood in Buffalo.

Federal prosecutors returned the indictment against Gendron on Thursday, the same day that the Tops Friendly Markets store - the site of the shooting - held a moment of silence and prayer to commemorate the two-month anniversary of the May 14 attack.

The store, which has since been fully renovated with increased security systems and a victim memorial, reopened on Friday. Ten days after the massacre, a mass shooting at a school in Uvalde, Texas, left 19 children and two teachers dead.

Seven weeks after the Buffalo massacre, seven people were fatally shot at a Fourth of July parade in Highland Park, Illinois. The attacks have reignited a longstanding national debate over US gun laws.