Donald Trump weighed in on the sexual misconduct debate sweeping the world on Saturday, saying people's lives are "being shattered" by a "mere allegation".

The tweet came a day after the US president come under fire for his staunch defence of an aide accused of domestic violence, drawing criticism for neglecting to mention the two women making the allegations.

Mr Trump voiced sympathy for former aide Rob Porter, who resigned on Wednesday, and wished him well in his future endeavors.

"It's a, obviously, tough time for him. He did a very good job when he was in the White House. And we hope he has a wonderful career," Mr Trump said. "He said very strongly yesterday that he's innocent," he added.

Mr Trump's comments, which failed to acknowledge the alleged treatment of Mr Porter's two wives, drew immediate condemnation from Democrats and women's groups.

He later fuelled the controversy by tweeting: