Former US president Barack Obama has condemned language that feeds hatred and normalises racism, following two mass shootings within hours at the weekend, one committed by a suspected white supremacist.

The rare statement posted on Mr Obama’s Twitter account on Monday came as many commentators and Democratic politicians accused his successor, Donald Trump, of using rhetoric that has encouraged white nationalists.

“We should soundly reject language coming out of the mouths of any of our leaders that feeds a climate of fear and hatred or normalises racist sentiments,” Mr Obama said, without specifically mentioning Mr Trump.

“Leaders who demonise those who don’t look like us, or suggest that other people, including immigrants, threaten our way of life, or refer to other people as sub-human, or imply that America belongs to just one certain type of people.”

Such language had “no place in our politics and our public life,” he said.

“It’s time for the overwhelming majority of Americans of goodwill, of every race and faith and political party, to say as much – clearly and unequivocally.”

Saturday’s shooting at a Walmart in El Paso, Texas, that killed 22 people is being treated as a hate crime after the main suspect had posted an online rant praising the Christchurch massacre and white supremacy shortly before the attack.

It was followed within 20 hours by another mass shooting that claimed nine lives, including the gunman’s sister, in Dayton, Ohio.

Police have said that the suspect in Ohio, who was shot dead within seconds, showed no sign of race as a motivating factor. However, he is reported to have made other threats of violence in recent years.

pic.twitter.com/nNOVtQ50O4

— Barack Obama (@BarackObama) August 5, 2019

Mr Obama also advocated the introduction of stricter gun control laws, something he tried and failed to do while president.

“Every time this happens, we’re told that tougher gun control laws won’t stop all murders; that they won’t stop every deranged individual from a getting a weapon and shooting innocent people in public places,” he said.

“But the evidence shows that they can stop some killings. They can save some families from heartbreak.”

Mr Obama’s statement was backed by another former Democrat president, Bill Clinton. He called for tougher gun laws to be reinstated.

“How many more people have to die before we reinstate the assault weapons ban and the limit on high-capacity magazines and pass universal background checks?” he said.

“After they passed in 1994, there was a big drop in mass shooting deaths.”

How many more people have to die before we reinstate the assault weapons ban & the limit on high-capacity magazines & pass universal background checks? After they passed in 1994, there was a big drop in mass shooting deaths. When the ban expired, they rose again. We must act now.

— Bill Clinton (@BillClinton) August 5, 2019

Mr Trump, who last month said four female Democrats of colour should “go back” to where they came from, on Monday condemned white supremacy but stopped short of proposing specific gun control measures.

Instead he blamed the internet and video games for glorifying violence and called for a reform of mental health laws.

“Mental illness and hatred pulls the trigger, not the gun,” Mr Trump said.

-with AAP