South Shields MP Emma Lewell-Buck has called on police to say how many families are involved in the human tissue probe at South Tyneside District Hospital.
Mrs Lewell-Buck says it is a matter of transparency that the scale of the operation is made public.
Northumbria Police will still not say how many families are involved in the investigation - which was launched after organs and body tissue was found to have been kept “longer than necessary.”
Some of the material - taken as part of criminal and inquest investigations - dates back 20 years.
The samples were found at the hospital, in Harton Lane, South Shields, during an audit two years ago.
Mrs Lewell-Buck said: “It will be extremely distressing for the affected families to learn of these findings.
“I am disappointed to hear of this situation and I trust that measures are now in place to ensure robust procedures going forward.
“In such circumstances it is important that families are given as much information and support as they require to help them come to terms with their renewed grief.
“It is also important that transparency on the facts of this audit and scale of the findings is evident in the wider public interest ”
Police say they have sill to contact a number of families as a probe continues.
It is understood that the number of families is in double figures.
Cleveland Police has already confirmed it is speaking to 13 families, but Northumbria says it has decided not to make public how many people are involved.
A spokeswoman for the Northumbria Police said: “Our specially trained officers are in the process of locating and speaking to the families affected, which will take some time as some next of kin do not live in the North East. “Officers are visiting each family in person to provide information and support to them.”
It is understood the samples were taken to the hospital by a pathologist who covered a large area of the North East.
Police forces nationwide began carrying out audits in 2010 after it became apparent human tissue samples going back many years may have been retained.
All the cases in South Tyneside pre-date 2006, when the Human Tissue Act 2004 came into force. The audit was completed in March 2015 and police were made aware that some human tissue samples had been identified at South Tyneside District Hospital that have been kept longer than necessary. The Human Tissue Authority said they will be keeping in contact with those involved.
Health Watch South Tyneside did not want to comment on the investigation.