An inquiry into child protection issues began at a local authority under fire over the deaths of seven children.
The mayor of Doncaster, Martin Winter, commissioned the internal investigation after an Ofsted inspection branded children's services in the borough "inadequate" last month.
Seven children have died in the area since late 2004 in cases involving abuse or neglect.
Serious case reviews have been commissioned to find out what mistakes were made in each incident, although so far only three have been completed.
After an emotional emergency meeting of Doncaster councillors on Tuesday, local politicians questioned how long Mayor Winter had known about the failures of the children's services, and whether more could have been done to save the lives of vulnerable children.
It emerged that senior council managers met with union representatives in October 2007, after the deaths of just two children, to discuss problems within the department.
Jim Board, Doncaster's Unison branch secretary, said council officials were frank about failures within the authority.
He said Jayne Jack, the council's interim service manager, started the meeting by "saying that children's services were in crisis, and in many areas barely compliant with legislation".
Mr Board said the deaths of the children were mentioned at the meeting, which focused on making changes to the service to ease workloads of social workers and address their concerns. But between December 2007 and May 2008 a further five children died in the borough.
Mayor Winter, who dismissed calls for his resignation at the meeting, accepted some responsibility for the spate of deaths, but insisted he only knew about the full extent of the situation early in 2008, shortly before he brought in Dr Paul Gray as interim head of the children's services department last April.
