Kim Kardashian is urging her fans to take action after two African-American men were killed by police officers this week (ends08Jul16).

Many celebrities have taken to social media to express their sadness and to call for change after Alton Sterling and Philando Castile were shot dead by cops in separate incidents in Louisiana and Minnesota this week, and Kanye West's wife has now offered up an impassioned open letter on her website, telling fans she is "appalled and completely heartbroken" after watching the videos of the "two innocent black men, get senselessly murdered by police officers."

The mum-of-two reveals in the missive she wants her kids to respect police officers, but she also hopes they will feel safe around cops, no matter what colour their skin is.

"I do not ever want to have to teach my son to be scared of the police, or tell him that he has to watch his back because the people we are told to trust - the people who 'protect and serve' - may not be protecting and serving him because of the color of his skin," she continues.

The 35-year-old is also calling on her fans to peacefully come together and not be violent towards law enforcement officers.

"The last thing we need is to fuel anger with more hate or violence, especially toward the many incredible police officers who risk their lives every single day to protect our families and communities," she adds. "We must peacefully use the power of our voices and the strength of our numbers to demand changes in the judicial system so that brutality doesn't ever go unpunished."

"It is our responsibility as Americans and as parents to create a safe future for our children," she continues. "We must do something NOW. We must speak up until we are heard and real, effective changes are made."

The Keeping Up with the Kardashians star concludes her message by providing information about local legislators, charity sites for Sterling and Castile's families and links to the Black Lives Matter campaign to her readers. She also lists other police brutality victims.

"Hashtags are not enough," she writes. "This must end now."

Her comments were posted hours after an ambush attack in Dallas, Texas on Thursday night (07Jul16) left five police officers dead and seven others wounded.