LibDem leader Willie Rennie joined a crew in Perth and criticised the decision to turn away a vital contribution.
However, Police Scotland insisted: "We fully recognise the valuable work many volunteer organisations perform and recognise the previous commitment of those operating the Sky Watch service. However, it is important this is done in a safe and lawful way. The availability of the Police Scotland Air Support Unit, together with legal advice has meant no requirement for the voluntary service."
Scots LibDem leader Willie Rennie said: "When someone goes missing we need to be doing everything to locate them. No-one is faulting the professionalism of police but Sky Watch offer a proven service which costs Police Scotland nothing."
Tony Cowan, chairman of the UK Civil Air Patrol, said: "We would welcome the chance to discuss the future of Sky Watch and hope they will reconsider their decision to cut ties so suddenly."