A union leader has claimed that up to a 1,000 jobs could be lost if the four Welsh police forces are merged.
Unison's Jean Brady claimed 1,000 police jobs could be lost
Jean Brady, a Unison organiser for Wales, said the option of merging Wales' forces would lead to job cuts.
The warning came as a cross-party Welsh assembly committee considered evidence on police reorganisation in Wales.
Home Secretary Charles Clarke has said some of Wales and England's 43 police forces are likely to merge to form larger units.
Mr Clarke has said all forces must reorganise to meet 21st century threats including organised crime and international terrorism.
One of the options being considered is to merge the four Welsh forces - South Wales, Dyfed-Powys, Gwent and North Wales - into one larger all-Wales unit.
Ms Brady said that such a reorganisation would lead to major job losses among police officers.
She told BBC Wales: "If there is restructuring in Wales as people are talking about, which is one force, then potentially we are talking about 1,000 jobs being lost throughout Wales in different roles.
"The knock-on effect is not having the jobs done at local level.
"I think there will be a knock-on effect for the force as well in losing all that expertise.
"The money they've spent on training people and then to lose them to outside organisations is not money well spent."
Charles Clarke has indicated he would prefer an all-Wales force
Ms Brady's warning came as a cross-party social justice committee at the Welsh assembly completed on Wednesday their review into the way policing is organised.
The committee considered several options and their conclusions will form part of the assembly's advice to Mr Clarke.
First Minister Rhodri Morgan has said the future of the four forces in Wales remains "up for grabs", despite Mr Clarke's preference for a single force.
Responding to a question in the assembly regarding the Unison claim that up to a 1,000 jobs could be lost in reorganisation, Welsh Social Justice Minister, Edwina Hart, said that although she had held meetings with Unison representatives, she could not recall that figure being raised.
But she added that she would certainly expect "major consultations if any of these issues arise."
'Cause for concern'
She said that if any job losses were to follow, it was hoped they would come through "natural wastage" and that the levels of service to the public would not be compromised.
But Leanne Wood, Plaid Cymru's social justice spokesperson, said the figure of 1,000 job losses could have an impact on services.
She added: "I don't think anybody's heard that figure, but obviously it is a real cause for concern.
"We've been told there are going to be efficiency savings as a result of this...it looks though that's jobs and that's a big problem.
"If we are to lose 1,000 people, I can't see how the same level of service can be provided."
Police forces have to submit their preferred options for reorganisation to the UK government by 23 December.
In two areas - Wales and north-east England - Mr Clarke indicated that only a single force would get his backing, and that "other stand-alone and merger options were assessed as unsuitable".