The loss of a youth mental health service in the Nelson Marlborough region's been put down to Government under-funding.

The Nelson Marlborough DHB is cutting its Child and Adolescent After Hours Crisis Service.

It's set be merged into the Adult Mental Health Service.

PSA organiser Mike Cunliffe said the DHB simply can't afford to provide the service any longer.

"Children and adolescents will be at risk and they just won't get the same level of service that they have had," he said.

"This has been a successful service and it has contributed to lower youth suicide figures in the Nelson/Marlborough area."

Mr Cunliffe said that the Government has under-funded the health sector to the tune of $2 billion since taking office.