Anti-second home posters seen in parts of North Wales and on social media have been reported to the police as a potential hate crime.
The abusive comments imply a return to the firebombing campaign of the 1980s by the nationalist group Meibion Glyndŵr, which was behind an estimated 200 arson attacks on holiday lets and private properties four decades ago.
Local media report that pictures of the provocative stickers have been shared on Welsh social media groups and one was spotted late last month on a road sign in Gwynedd.
The Daily Post news website says one commercial website is selling packs of stickers at £5.50 for 24. They say ‘F*** Your Second Home” and underlaid with the flag of Wales.
Others allegedly make obvious the implied threat of a fire in holiday properties.
Gwynedd council has already taken significant financial action against second homes, with a 150% council tax levy. It is also launching a bid to make the use of a home for a holiday let subject to a mandatory planning application.
It is the first ever council to try this tactic and it is seeking to win Welsh Government consent for it to introduce a so-called Article 4 direction, which means a planning application has to be submitted and agreed to, before a home can be short let or listed for holiday letting.
The Welsh Government last year announced a series of measures to reduce the number of second homes and short-lets: amongst them, planning legislation was amended to allow local planning authorities like Gwynedd to use an Article 4 Direction to control the use of houses as second homes and holiday accommodation.