Concerns the Government's won't keep its election promise of lowering the bowel cancer screening age to 45

The age will be lowered to 58 on Monday for Northland, Auckland, and the South Island - with the rest of the North Island to follow next year.

Health Minister Simeon Brown, says access to more colonoscopies will key to bringing the age down further.

But Labour Party health spokesperson Ayesha Verrall says the age could already be brought to 50, without the need for additional capacity.

She says freeing up resources, could be an opportunity for the Government to cut funding.