Older teenage girls are most at risk of sexual abuse, a new report has found.

An estimated 50,000 girls between the age of 16 and 17 years old have been victim of sexual exploitation, rape or sexual assault, a study by The Children's Society found. This is higher than for any other age group.

Although the group is more vulnerable than other age groups, they receive less protection and support than younger children. This is because they are seen as being "old enough to know better" as they have reached the age of consent, the charity said.

Children's Society is calling on the government to improve safeguards for older teenagers and address the perception that once a girl turned 16 she could "look after" herself.

The report also emphasised the disparity between the estimated number of assaults and the number of cases reported. The Children's Society compared figures from the crime survey for England and Wales with statistics obtained through freedom of information requests.

Fewer than one in ten cases of sexual abuse against 16 and 17 year old girls were reported to the police. Tens of thousands of sex crimes against teenagers go unreported because they are afraid they will not be believed, the report found.

Half of those who did not report sexual crimes to the police said it was because either they did not consider it worth reporting, or they feared going to court or because they did not want the perpetrators punished.

"Too many children are being left to suffer sexual exploitation in silence. Despite 16 and 17 year olds being at the highest risk, they often receive the least support," said Matthew Reed, chief executive of The Children's Society.

"Dangerous inconsistencies in the law and services need to be changed. These young people are still children and the Government must make sure that the police and other agencies have the means they need in order to keep them safe."

The report entitled Old Enough To Know Better? Why sexually exploited teenagers are being overlooked found that of the minority of cases that are reported to the police, fewer than 1 in 5 resulted in a charge or summons.