Facebook chief executive Mark Zuckerberg has promised to review the social network's policies, after facing backlash over his refusal to moderate controversial messages from US President Donald Trump. Zuckerberg has faced a raft of criticism for his stance, including from within Facebook itself – leading employees to quit in protest. The backlash was sparked last week after Trump posted messages to his Facebook and Twitter pages that included the phrase “when the looting starts, the shooting starts”, which has racist origins, while referring to those in the US protesting the death of George Floyd. Floyd, an unarmed black man, was killed in police custody after a white policeman knelt on his neck. As a result, Trump's tweet was hidden behind a warning that it “glorifies violence”. Twitter, and chief executive Jack Dorsey, had only last week reversed its stance on refusing to censor Trump, updating its policies and vowing to take action against inflammatory content. Trump responded by accusing Twitter of stifling free speech and vowing to regulate the social media giant. However, Zuckerberg had remained resolute in his position to not remove or flag Trump's posts that appeared to encourage violence against those protesting police racism. But on Friday afternoon, Zuckerberg appeared to change his stance on the matter. In an announcement, which was sent as a letter to employees and also appeared as a lengthy Facebook post from Zuckerberg's account, he outlined the social network's aim to "play a positive role in helping to heal the divisions in our society". "I also want to acknowledge that the decision I made last week has left many of you angry, disappointed and hurt," Zuckerberg said. "So I am especially grateful that, despite your heartfelt disagreement, you remain focused on taking positive steps to move forward. That can't be easy, so I just want to say I hear you and I'm grateful." Zuckerberg then went on to list the three categories the company would be exploring, based on feedback from employees, civil rights experts and subject matter experts. These are: ideas related to specific policies, ideas related to decision-making, and proactive initiatives to advance racial justice and voter engagement. "We're going to review our policies allowing discussion and threats of state use of force to see if there are any amendments we should adopt," Zuckerberg wrote. This would include "excessive use of police or state force". Zuckerberg also addressed internal complaints that minorities had not been adequately represented at the company. "We're going to review whether we need to change anything structurally to make sure the right groups and voices are at the table," Zuckerberg said.