WASHINGTON (AFP) - US First Lady Melania Trump renewed her campaign to tackle cyber bullying Monday (Aug 19), as her husband lit up the internet with a stream of invective against his perceived foes.

Appearing at a health department building outside Washington, the Slovenia-born first lady urged tech companies to listen more to "children's ideas and concerns" about online bullying.

"Let's face it: most children are more aware of the benefits and pitfalls of social media than some adults," she said.

"In today's global society, social media is inevitably a part of our children's daily lives. It can be used in many positive ways, but also can be destructive and harmful when used incorrectly," she said.

Since coming to office Melania Trump has spoken relatively infrequently in public.

She was treated at Walter Reed hospital on May 14 for what aides called a "benign" kidney condition and was released a few days later.

Her signature "be best" campaign for public decorum has been largely overshadowed by her husband's daily insults and public hectoring.

On Monday morning, he called the taxpayer-funded lawyers and prosecutors investigating Russia's influence in the 2016 election a "National Disgrace." Stephanie Grisham, the first lady's communications director, decried the media's focus on Trump's cyber activities.

"The First Lady's presence at events such as today's cyber bullying summit elevates an issue that is important to children and families across this country," she said.

"She is aware of the criticism but it will not deter her from doing what she feels is right. The President is proud of her commitment to children and encourages her in all that she does."