Last month, a food stall assistant was sentenced to 23½ years in jail and given 24 strokes of the cane for sexually abusing his biological daughter.

The abuse started in 2011, when she was 11, and ended when she was 13.

There has been a spike in allegations of sexual abuse of children by their own family members, according to figures from the Ministry of Social and Family Development (MSF).

Last year, the MSF's Child Protective Service (CPS) investigated 107 allegations of sexual abuse involving children under 16 years old. The CPS investigated 82 similar allegations in 2015 and 56 in 2014.

Most sexual abuse cases involved allegations of molestation, according to the MSF.

The CPS generally handles only cases involving family members.

The MSF said that its protective service works with families and caregivers "to improve their circumstances to keep the child safe under their care", and undertakes social investigations into allegations.

The police handle the criminal investigation.

It stressed the importance of reporting sexual assault, even if the abuser is someone a victim knows or trusts, and tells the victim to keep it a secret.

For cases involving young people, parental guidance and support are particularly important, said Ms Lena Teo, deputy director for therapy and mental wellness services at the Children-at-Risk Empowerment Association.

Also known as Care Singapore, the organisation offers counselling services that support children, youths and their families.

Young victims of sexual assault could experience nightmares and shame, and show changes in behaviour such as refusing to attend school, she said.

"We always try to make sure that the parents have the proper education and are informed on how to deal with the situation," she added.

Ms Teo said that younger victims tend to harbour a sense of betrayal if the perpetrator was trusted, or someone they were dependent on.

They may also feel betrayed by a non-offending caregiver, who was supposed to protect and support them, she said.

In more severe cases, victims may show signs of post-traumatic stress disorder and experience flashbacks of the incident. Some may also harm themselves.

Separately, the State Courts had 64 convictions for cases involving sexual penetration of a minor under 16 last year. There were 66 convictions in 2015.

The Family Justice Courts also saw 57 offences for sexual penetration of a minor under 16, committed by young people. There were 26 such offences in 2015.