The pupils were on their way to lessons at Cefn Saeson School
A number of pupils have been suspended from a comprehensive school for smoking cannabis on their way to lessons.
The teenagers, thought to be four in number, were temporarily excluded from Cefn Saeson School in Cimla, Neath.
Neath Port Talbot council's education department said the incident took place off school premises and before the school day had begun.
It said police had been informed and the 'small number of pupils' offered substance misuse support.
The pupils will be allowed to return to school after the suspension.
Council head of schools Aled Evans said: "Acting on information received, Cefn Saeson Comprehensive School has taken disciplinary action against a small number of pupils who have admitted to smoking cannabis whilst on their way to school.
"The incident took place off school premises and the police have been informed.
"The pupils are being offered support from specialist services dealing with substance misuse and the school will also provide support and guidance to the pupils on their return.
"Staff in Neath Port Talbot schools are well placed to provide help and guidance to young people who become involved in drug-related issues."