Campaigners have highlighted a "worrying" disparity in the number of children across Scotland who receive additional support while at school.

According to the figures for 2015, Aberdeenshire had the highest proportion of pupils who were classed as having additional support needs (ASN) with 35.7% of schoolchildren requiring some form of extra support.

But there were four other local authorities also reporting about a third of students with ASN - West Dunbartonshire (35.3%), Highland (33.6%), the Western Isles (33%), and Perth and Kinross (32.8%).

In North Lanarkshire, only 8% of youngsters were in this category, but in neighbouring Glasgow the total was much higher at 29.8%.

Similarly, in South Ayrshire 11.6% of pupils were recorded as having ASN, compared to 27.1% in nearby North Ayrshire.

The figures, revealed by Education Secretary John Swinney in answer to a parliamentary question, showed that across Scotland almost a quarter (22.5%) of pupils receive this support.

The Education (Additional Support for Learning) (Scotland) Act 2004 places a duty on local authorities to provide additional support where it is needed to enable any child or young person to benefit from education.

Children who receive the extra help include those who have behavioural or learning difficulties, youngsters who are deaf and blind, and children in care.

The Scottish Children's Services Coalition (SCSC), which brings together voluntary and independent sector care providers, said the disparity between areas suggests some children may not be getting the assistance they require.

It also warned that if some councils are not identifying all ASN youngsters, it could make it harder for ministers to meet their flagship pledge to tackle the educational attainment gap.

A spokesman for the SCSC said: "As a coalition we find it worrying at these major disparities which indicate, for example, that as a percentage of the pupil population nearly more than four times as many children and young people in Glasgow have ASN compared with North Lanarkshire.

"This inconsistency in gathering information on and identifying those with ASN by local authorities requires clearer and comprehensive guidance from the Scottish Government, which is also key if it is to close the educational attainment gap.

"The Scottish Government must commit to working more closely with local authorities to tackle this and develop a universal method to ensure that better information is recorded so that accurate numbers can be reported. Only then will we truly be able to provide the best support for some of Scotland's most vulnerable people."

Green education spokesman Ross Greer MSP said investment in ASN should be a priority for the Government rather than introducing standardised assessments in primary and early secondary.

He claimed this should be the case as "ASN disproportionately affects children from lower income households".

Mr Greer said: "Parents, pupils and teachers are being let down as the squeeze on public funds disgracefully targets ASN as a soft option.

"If we're serious about closing the attainment gap we must listen to those working with children who are being denied adequate funding to address learning difficulties, speech and behaviour and conditions such as autism."

A Scottish Government spokeswoman said: "We continue to work with partners in local authorities to share best practice and build on the attainment improvements already made. This includes pupils with additional support needs gaining better qualifications and going on to more positive destinations after leaving school.

"There has also been a significant increase in the number of pupils recorded in national statistics as having additional support needs since 2010 thanks to changes in the way we collect information.

"Prior to 2010, only pupils with Co-ordinated Support Plans, Individualised Educational Programmes or who were attending a special school were recorded as having additional support needs, however in 2010 this was extended to include anyone receiving additional support.

"In addition to this, the Scottish Government has also made a commitment to improve guidance to authorities on recording and work to agree this is ongoing."

A spokesman for the local government body Cosla said: "There is no postcode lottery in relation to children with ASN. Scotland's councils are absolutely committed to supporting children with additional support needs and work with a range of partners to fully support children with those needs.

"I am not sure as to the legitimacy of the figures - but in many ways that is irrelevant. Because the bottom line is that we are fundamentally committed to the needs of every young person and that means an approach more focussed on the individual than these figures would suggest - and that is the real story of what councils are about in relation to this."