Liberal Democrats Senator David Leyonhjelm has thanked "young brown men" for their contribution to Australia's workforce, in a speech that has been labelled "condescending".

Senator Leyonhjelm paid tribute to young migrants, from the subcontinent and the Middle East, for "turning up their sleeves" at jobs "many other Aussies would turn up their noses at".

"Let me say thank you to Australia's young brown men," Senator Leyonhjelm said.

SBS News

"They drive me in their Ubers and taxis. They deliver my online purchases, my groceries and my pizza. And they serve me at my local 7-Eleven, at my local service station, and my local restaurants.

"Many of these young brown men have only been in Australia for a decade or so, and they are giving it go, just like previous generations of young migrants."

The controversial figure, who was most recently embroiled in a war of words with Greens Senator Sarah Hanson-Young after telling her to "stop shagging men", then went on to say up to 40 per cent of recent immigrants settling in Australia were over-qualified for their job.

Mr Leyonhjelm said Australia was not taking advantage of the talent pool of its "young brown men", likely due to racial discrimination in the workforce.

"Australia may be squandering the talent pool of its young brown men and women," he told the Senate.

He finished the speech praising the hard work of "young brown men and women" for "changing the complexion of Australia for the better."

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But the speech was labelled "condescending" by Greens Senator Greens Senator Mehreen Faruqi.

"I would like to give Senator Leyonhjelm the benefit of the doubt in being sincere about his concern about migrants but condescending speeches don't help," the senator, who migrated to Australia from Pakistan in 1992, told SBS News.

"Migrants aren't sitting here plugging away passively waiting for the world to change, we are actively challenging racism and demanding our rights.

"If he was really concerned about migrants he wouldn't have just voted to take away their social security safety net should they find themselves in hardship."

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Democracy in Colour spokesman Tim Lo Surdo said that while migrants do often face workplace challenges, they are actively driving change in Australia.

"A third of Australia's temporary migrant workers are paid less than half the minimum wage. It is a crisis. But those same workers, they are fighting back," he said.

"These folks are leading the way. And to suggest that that work's not been happening, or that they need some sort of white saviour like Senator Leyonhjelm to swoop in and save the day, is not true. And it's very condescending, it's very patronising, and it makes invisible all of that work that is being done right now."

The speech follows previous calls from Mr Leyonhjelm for Australia to enforce an "entry fee" for migrants because they have not contributed to existing infrastructure.

It's not the first time the blunt speaking Liberal Democrat has attracted headlines. Earlier this year, he called then-PM Malcolm Turnbull a "pussy".

"This is about misandry. The prime minister should stop being such a pussy. This is about criticism of all men. It's just as bad as criticism of all women," he said in July.