At First Minister’s Questions, Tory leader Ruth Davidson described the situation as a “scandal” and called for a Holyrood inquiry.

Ms Davidson quoted work carried out by Professor Jim Scott, which found that subject choice fell dramatically when schools in poor areas were compared with those in the wealthiest areas.

The Tory leader said the “majority” of schools now offered S4 (14 and 15-year-old) pupils just six subjects, which meant “severely limited” options for those wanting to study sciences and languages.

“It is the poorest parts of Scotland that suffer the most,” Ms Davidson said.

Majority of Scots concerned how Brexit will impact on them

“If you go to a school in one of the wealthiest parts of Scotland, you have got a 70 per cent chance of being able to choose between 12 or more Advanced Highers.”

Ms Davidson then asked Nicola Sturgeon how many schools in the poorest areas offered 12 or more Advanced Highers.

After Ms Sturgeon failed to come up with the answer, Ms Davidson said the figure was two.

“There are just two schools in the poorest parts of Scotland where you can choose between 12 or more Advanced Highers and in the rest you get nowhere near that. That’s the reality in SNP Scotland,” Ms Davidson said.

The Tory leader quoted Professor Scott saying the academic had concluded that the S1 to S3 curriculum was in “serious disarray”.

“Pupils are then crashing down suddenly to as few as six subjects in S4, meaning they are effectively picking their Highers at the age of 14 and it is pupils in the poorest areas that are being hit hardest. There is a scandal going on in secondary schools right now and this government is curtailing the choice of our young people to pursue that same broad based education that the First Minister enjoyed, that I enjoyed, that generations of Scots have benefited from. It can’t continue. We support a parliamentary inquiry into this issue. Will the First Minister back it?”

Ms Sturgeon replied that there had been a scandal in Scottish politics this week and it had involved the resignation of one of Ms Davidson’s front-benchers. She was referring to Peter Chapman, the Tory who quit the front bench after a lobbying row.

Ms Sturgeon said: “I cannot believe that Ruth Davidson doesn’t think that’s what’s important is the Highers and other qualifications that our young people are leaving with.

“There are more young people, including in our most deprived communities, now leaving school with qualifications including Highers. There are more young people with Advanced Highers, a 40 per cent increase in our most deprived communities in the young people coming out of our schools with more Advanced Highers. More young people with more qualifications. That’s a sign of success of our education system, which is why the Tories don’t want to recognise it.”

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FMQs: Nicola Sturgeon tackled over school subject '˜scandal'