STOCKHOLM (AFP) - Sweden's schools were already struggling with demoralised teachers and declining test scores before the arrival of masses of young migrants whose needs have put unprecedented strain on the system.

Of the roughly 245,000 migrants who have arrived in the Scandinavian country since 2014, 70,000 are under the age of 18.

The majority of these youngsters are Syrians, Afghans and Iraqis who have been robbed of a proper schooling by war and exile.

Their standard of education often lags far behind their Swedish peers' and, in addition to learning a new language and alphabet, they must also adapt to new ways of thinking and learning.

"It's a real challenge," Education Minister Gustav Fridolin said in an interview with AFP.

The Swedish school system already faces major challenges including an acute shortage of qualified teachers - 60,000 more are needed by 2019 - and declining scores in standardised international tests.

The quality of education can also vary significantly from school to school.

A Unicef report published in April showed that Sweden, along with neighbouring Finland, is the country where school results declined most between 2006 and 2012.

The Swedish National Agency for Education blames the decline in school performance on the large number of foreign students who they say drag down results because of language issues.

In 2014, 14 percent of students had results too low to qualify for the second part of secondary school (for students aged 16 to 18), a 10 per cent deterioration on the 2006 level.

The lower level of pupils qualifying for further education was due to the rising number of students who migrated to Sweden after school starting age - six-years-old in Sweden - who struggled to catch up as a result, according to the report.

Mr Fridolin said that it is "much more costly" for society to pay for a school system that has failed migrants than it is to give them a good education in the first place.

More than 20 per cent of people born abroad are unemployed in Sweden, compared to around five per cent of those born in the country, according to Statistics Sweden.

The far-right Sweden Democrats party, which regularly criticises the government for its handling of the migrant influx, sees the declining school scores as a consequence of growing segregation in Sweden.

In the Sodertalje municipality south of Stockholm, 37 per cent of residents are born abroad. Three years ago, authorities decided to assign two teachers to each primary school class to ensure students got the attention they needed.

"The students get more help, the classes can be adapted to their needs and the teachers feel less stressed," said Sodertalje's head of schools, Ms Monica Sonde.

The gamble seems to be paying off, with the number of students qualifying for upper secondary school on the rise.

At the Wasa primary and middle school, 90 per cent of students speak Arabic and almost one in five students arrived in Sweden in the past two years.

But Mark Khoazzoum, an 11-year-old whose father was a doctor in Aleppo, Syria, needed just three months in an adaptation class before he was ready to move into regular lessons.

He now speaks good Swedish. But the language "is still an obstacle when I want to describe things," he said.

The scale of the challenges facing new immigrants varies depending on their country of origin.

"Syria has a pretty adequate school system while countries like Iraq, Afghanistan and Somalia have very weak school systems, which means that students from these countries may not have attended school before arriving in Sweden," said Mr Anders Auer, a policy analyst at the country's education agency.

Newly-arrived children are usually placed in adaptation classes where they learn Swedish, their knowledge levels are tested and they receive schooling in their mother tongue.

Within two years, they are expected to have caught up enough to be able to enter the regular curriculum.

They usually face hurdles all they way through their education, but "in our statistics, we have noted that the foreign students are more motivated than those born in Sweden," said Mr Auer.

And until the conflicts raging in the Middle East abate and the flow of migrants begins to slow, the pressures on Sweden's schools and teachers will only continue to grow.

"Even though they're motivated they have a hard time," said Mr Auer.