Tomboy girls who play with boys toys are more likely to be autistic, concerning new research today suggested.

Swedish researchers, who analysed data on more than 700 children, found girls who engaged in more 'masculine play' were at higher risk of having 'autistic traits'. 

Yet boys who preferred to play with dolls were more likely to have relationship issues with other kids. 

But the scientists, from Karlstad University, acknowledged their findings do not prove a definite 'link to behavioural difficulties or autistic traits'. 

Using surveys, they analysed how the children, aged seven on average, liked to play and their behaviour.

Gender nonconformity (GNC) in play was determined using 12 'feminine' and 12 'masculine' toys, play activities and child characteristics.

For example playing with toy guns, trains, airplanes or swords would typically be characterised as 'masculine', while playing with jewellery, playing house such as pretend cleaning or cooking, or dressing up in 'girlish' clothes would typically be considered 'feminine'.

In both sexes, higher levels of GNC play was linked with increased behavioural difficulties including hyperactivity and inattention.

Analysis also revealed that higher feminine play scores in boys were linked with peer relationship problems, while higher masculine play scores in girls were linked with an increased likelihood of autistic traits.

'The results showed that children who played more with toys traditionally considered for the opposite gender had more autistic traits and behavioural problems,' the researchers said.

'At the same time it is very important to keep in mind that just because a girl decides to play rougher or a boy plays with dolls, it does not mean that there will be a link to behavioural difficulties or autistic traits in this child.' 

Author Marlene Stratmann added: 'Based on our research we can say that we did see a 7 per cent increase in autistic traits for girls that expressed a more masculine play behaviour compared to girls that expressed a more feminine play behaviour.

'It is important to keep in mind that we only had access to autistic traits and not autism diagnoses and also that we conducted a cross-sectional study and are unable to tell if the play behaviour increased the risk for autistic traits in girls or if it is vice versa.'

The findings were published in the journal Plos One.

Recent studies have already begun to suggest a link between gender nonconformity, gender dysmorphia and autism.

One found that people who do not identify with the sex they were assigned at birth are up to six times as likely to be autistic.

Last year, it emerged that an NHS children's gender clinic 'ignored' evidence that 97.5 per cent of kids seeking sex changes had autism, depression or other problems.

Clinicians who worked at the Tavistock Clinic said they feared they could be 'unnecessarily medicating autistic children' who were treated as 'collateral damage'.

Seventy per cent of children referred to the service had more than five 'associated features' such as abuse, anxiety, eating disorders or bullying, the book reveals.

Dr Anna Hutchinson, a senior clinical psychologist at the Gender Identity Development Service (Gids), who joined at the start of 2013, said she was 'horrified' at the possibility that the service was 'getting it wrong'. 

It is estimated that around 700,000 Brits and 5.4 million adults in the US have an autism diagnosis.

According to a 2021 Newcastle University study, around one in 57 (1.76 per cent) children in the UK is on the spectrum.

Having autism means a person's brain works differently to normal.

It's not a disease and people have it from the moment they are born, although it may not be spotted until childhood and sometimes much later.

Autism exists on a spectrum. Some people will be able to lead fully functioning lives with no additional help. Others may need full-time assistance.

Classic signs of autism include trouble communicating, finding certain situations overwhelming and repetitive behaviours.

Rates have spiralled in recent years, sparking suggestions that the disorder is now being overdiagnosed. 

In April it was revealed that children across the UK are waiting up to four years for a diagnosis of autism.