The increase of foreign-born children in Swedish schools has played a part in the country's overall decline in educational achievement and test scores in recent years, officials report.

The number of teenagers who failed to qualify for upper secondary school in Sweden increased from ten per cent in 2006 to more than 14 per cent in 2015.

A report by the Swedish Education Agency released on Monday concluded that 85 per cent of the increase was explained by immigrant students unable to catch up with Swedes of the same age.

Decline in standards: The number of teenagers who failed to qualify for upper secondary school in Sweden increased from ten per cent in 2006 to more than 14 per cent in 2015.

Over the past decade, Swedish test scores on the OECD's so-called PISA ranking of school performance among 15-year-olds has seen the most dramatic drop out of all the countries taking part in the survey.

At the same time, the percentage of students in Swedish schools who had arrived in the country after the age of seven jumped from three per cent in 2006 to eight per cent in 2015.

The report, entitled The Importance of Immigration for School Results, defines 'immigrant students' as children who are either foreign-born or whose parents are both born outside Sweden.

It concluded that as immigrant students now arrive in greater numbers and at an older age, they had less time to learn Swedish and catch up in vital subjects before leaving Year 9.

As a result, an increasing number of foreign-born students fail to obtain the grades needed to move on to Swedish upper secondary school - equivalent to A-levels or High School.

Sweden has had the most dramatic drop in PISA performance out of all the countries taking part in the survey

'We already know that immigrant students on average have lower performance in school,' said Education Agency Director Anna Ekstrom.

Now we know more about how much the increasing proportion of immigrant students has affected overall performance.'

Sweden's performance in the OECD's PISA survey has also 'declined over the past decade from around average to significantly below average.

'No other country taking part in PISA has seen a steeper fall,' the OECD said in a 2015 statement.

'In the most recent test in 2012, Sweden ranked 28 among the 34 OECD countries in mathematics, 27 in reading and 27 in science,' the Organisation for Economic Co-operation and Development said.

According to Sweden's education agency, the unprecedented wave of asylum seekers who have arrived since 2014 should increase this trend.

Of the 163,000 asylum seekers who arrived in Sweden last year, 43 per cent were minors, according to the Swedish Migration Agency.