Vulnerable children under the care of Waltham Forest council could be at risk as permanent social worker positions remain unfilled, it is claimed.

According to figures released last month, 45 per cent of such posts in the borough are carried out by temporary workers – the largest vacancy rate in England.

The national average is 11 per cent, with 28 per cent of positions unfilled in Rochdale where dozens of girls were the victims of child sexual exploitation in recent years. 

Waltham Forest social services was rated inadequate in 2012 and served with an improvement notice which was closed in February 2013. 

The local authority currently cares for 250 children.

The British Association of Social Workers (BASW) has warned that unfilled posts are compromising vulnerable chidren’s safety

Officer Nushra Mansuri said: "It will up the ante. Risk is risk - we are talking about children who largely are at risk, and the system can make that riskier if people have not got enough capacity to do that work rigorously and thoroughly. 

"It's not rocket science. If we give people way too much work beyond their capacity then it's not going to work and it's not good for those children. It makes their situation more vulnerable." 

A council spokesman said many agency workers had worked in the borough for some time and built "meaningful and supportive relationships" with service users. 

He continued: "Like most social work employers, and in particular London boroughs, we have a social care workforce made up of permanent and agency colleagues.

"All of our social work posts are currently filled and we have a recruitment and retention strategy which means we are seeing an increase in our permanent workforce.

"Our current caseload is not unmanageable and feedback from social care staff supports this.

"Our caseloads and performance is regularly open to independent scrutiny by councillors, and Ofsted have found that no children were left unprotected from significant harm."