Squatters

If I understand correctly (still not 100%) - "you" are the members of the urbanisation's committee. The property in question is currently owned by a bank. In that case, there is almost certainly nothing "you" can do, since it's not your property. Other than notifying the bank (owner) and hoping they do something about it. 

Unless the "squatters" have a rental contract or escritura to show they have a right to occupy the property, I can't see any electric company connecting a power supply for them. If the meter has been removed, the only way they can be getting electricity is by tapping into someone else's. 

Sorry, can't offer anything more.

P.S. Are you the same community as the one mentioned here? https://www.eyeonspain.com/forums/posts-long-22819.aspx

Thanks roberto

no I'm not the same as the other post.

Are those properties owned by Banks?

As a community, ask Banks to take an active play on this, as this affects the whole community. You can start judicial actions regarding this lack of care.

I would also report it to the Housing Authorities in your town and region for them to force the Banks to manage this in favour of people who needs the properties and will pay for them.

This link might be of your interest:

http://www.elperiodicomediterraneo.com/noticias/castellon/vivienda-obliga-bancos-ceder-ya-pisos-alquilar_1056837.html