A Tory minister was branded a "pantomime villain" as he stonewalled calls to bring in pay equality for all ages.
Under current legislation younger workers can be paid less, despite doing the same job.
SNP MP David Linden, who secured a Commons debate on the issue, told ministers the law was "ludicrous", but business minister Andrew Griffiths gave a bold defence of the policy, telling MPs the differing rates helped young people into work.
His response to the debate drew jeers from the SNP benches, with Chris Stephens branding him a "pantomime villain" and Mr Linden telling him he had "demeaned his office".
Since April 1, workers over the age of 25 are entitled to a minimum wage of £7.83 an hour, while those aged 21 to 24 are only entitled to £7.38, 18 to 20-year-olds are entitled to £5.90, those under 18 are entitled to £4.20, and apprentices can be paid as little as £3.70 an hour.
Mr Linden said: "Quite rightly the 2010 UK Equality Act makes provision for a number of key protected characteristics, indeed it prohibits discrimination on the grounds of gender, race, sexual orientation or disability.
"How therefore can we have a ludicrous position in which people under 25 are paid less simply for being a particular age.
"We wouldn't say to someone that they should be paid less because they're a woman, we wouldn't say to someone they should be paid less because they're black, we wouldn't say to someone they should be paid less because they're gay and we certainly wouldn't say someone should be paid less because they're disabled.
"Yet we have under the UK Government a system where employers are actively encouraged to pay under 25s less because they're younger."
Mr Griffiths responded: "Low pay rates have always been in place for younger workers, the reason for this is because the priority for younger workers is to secure work and gain experience.
"A higher minimum wage for young people could adversely effect employment levels for this group by dissuading employers from taking on less experienced workers."
Mr Griffiths then told Mr Linden it was "remarkable" he had not touched upon the unemployment rates among young people in his speech.
He said: "For 18 to 24-year-olds the unemployment rate is 10.3% and more than one in four 16 and 17-year-olds are unemployed.
"He says we should focus on the individuals and not the statistics, but those statistics show very clearly the impact that his policy would have on those young people and their ability to get into work."
Mr Linden, later intervening, said: "The patronising tone he's taken in this debate has demeaned his office and I hope that he'll reflect on that afterwards."
Mr Griffiths then rose to continue speaking, at which Mr Linden said, "Have a wee seat 'cos I'm not finished", before again outlining rates of pay for apprentices.
The minister concluded by telling MPs the Government was "committed to building an economy that works for everyone".