Almost one in five 13-year-olds have been offered drugs, according to a new survey about substance use among Scottish school pupils.

The latest Scottish Schools Adolescent Lifestyle and Substance Use Survey (Salsus) found the number of 13 and 15-year-olds who said they had been offered drugs had increased by 5% between 2013 and 2015.

The survey, which questioned 25,304 pupils across 264 schools, found 19% of 13-year-olds and 42% of 15-year-olds had been offered drugs.

It also showed 4% of 13-year-olds had drank alcohol in the week before the poll, 3% had used drugs and 2% smoked regularly, compared to 17%, 11% and 7% of 15-year-olds.

The number of 15-year-olds who smoke regularly fell by 2% between 2013 and 2015, while the rate for 13-year-olds remained much the same.

A large increase in the amount of pupils trying e-cigarettes was also found, with 15% of 13-year-olds and 32% of 15-year-olds having done so.

Of the 13-year-olds who regularly smoke, one in five said they bought their cigarettes from shops.

The most common source of cigarettes for both ages groups was getting someone else to buy them for them.

Sheila Duffy, chief executive of anti-smoking charity Ash Scotland, said there is "no excuse" for shopkeepers to sell tobacco to children.

She said: "Fewer children than ever are now taking up smoking, putting us well on the way to a tobacco-free Scotland by 2034.

"We need to keep up the pressure so no child becomes addicted to tobacco and make sure that the best help to quit is available for those who've already started."

Aileen Campbell, minister for public health and sport, said: "We welcome these encouraging findings that show smoking, drinking alcohol and drug use among young people are now amongst the lowest levels recorded by the survey.

"The drop in drinking, smoking and drug use in recent years is testament to the significant work being done around the country with young people to promote positive alternatives to substance use.

"We are continuing to take action to protect and support young people through measures such as improved substance misuse education in schools, strengthening legislation and supporting children affected by substance misuse."