Donald Trum

He told Fox News the Democrats were putting out the reports because they were embarrassed at the scale of the election defeat.

On Friday, CIA officials told US media they had concluded that Russians hackers were trying to help Mr Trump.

Russian officials have repeatedly denied the hacking accusations.

Mr Trump said it might have been Russia but it was impossible to know.

"They have no idea if it's Russia or China or somebody sitting in a bed some place," he said.

Mr Trump made the remarks when asked if he supported more profiling of Muslims in the US, in the context of last week's shooting at an Orlando gay club.

Profiling uses ethnicity, race and religion to determine whether a person has or is likely to commit crimes.

Critics say it could alienate Muslims.

In an interview with CBS, Mr Trump said other countries had "successfully" adopted the measure.

"I hate the concept of profiling but we have to start using common sense," he said.

Obama's extraordinary denunciation of the presumptive Republican presidential nominee was about far more than a personal intervention on behalf of Hillary Clinton in the ugly general election campaign.

The commander in chief's fury, which seethed out of him in a stunning soliloquy on live television, amounted to a moment of historic significance: a president castigating one of the two people who could succeed him as beyond the constitutional and political norms of the nation itself.