Family Mediation South Lanarkshire (FMSL) runs two child-contact centres, one each in East Kilbride and Hamilton, where children can spend time with either or both of their parents, when there has been an acrimonious split.
But after a block of one-off Scottish Government funding ran out, the service at both centres has been reduced.
The Hamilton child contact centre, based at Burnbank Family Centre, used to be open from 10am to 4pm on Saturdays and Sundays.
That will be reduced to 10am to 4pm on Saturdays and 10am to 1pm on Sundays.
The East Kilbride service, based at the Cedarwood Centre, previously ran from 10am to 4pm on a Saturday but will now run from 10am to 1pm only.
A grant of around £32,000 from the Scottish Government's Resilience Fund was allocated to FMSL in 2009 which allowed them to increase the contact centres' opening hours and employ a full time manager.
But with that money now having run out, some families will lose out on the vital service. FMSL service manager, Mark Stalker, said: "The child contact centres offer a vital service which helps many children to spend time with both of their parents.
"Without the centres, a lot of children would never get to see one of their parents if there has been an acrimonious separation.
"During the recession there was a huge rise in the number of people using the service and we were given the funding to expand.
"It was a great to be able to do that, but unfortunately now the funding has run out and we have to cut back on the hours. It means that a number of families who use the service will lose out.
"It's one of these services that most people won't even know exists, because you've not been in the situation where you need that kind of help.
"But it is an absolutely vital service and we hope we can find alternative funding to increase the opening hours again."
To find out more about the services offered by FMSL, go online to www.familysupport.org.uk or call 01698 421 333.