Hello number stations fans..
Sometimes not going to sleep and instead randomly emailing your government at 5 AM about spy stuff can be a bad idea.. However as it turns out - it wasn't a bad idea in my case at all!
But what a surprise - they actually admit OLX was a Czech(oslovak) spy station!
Here's the full email (translated by me) as sent by Petr Cink from 5th secretariat (IT and Communications Operations Department) of the Czech Ministry of Interior, which officially admitted to running - and sent QSL cards from this station in the 1990's.. Thank you very much Petr!
it was shortwave broadcasting into foreign countries, which was being conducted by the Úřad pro zahraniční styky a informace [Office for Foreign Relations and Information] (formally belonging under the Ministry of Interior).
Confirmation of listener's reports was likely done by someone from the MoI's old Section of Communications, probably the operations department, that was seated in 6th floor in Olšanská (the address was Box 21/SK).
MoI has already stopped shortwave broadcasts many years ago under administration existing at the time.
So, there you have it. Some countries actually have balls to admit what the numbers really mean :-)
It is worth adding that ÚZSI is the Czech Foreign Intelligence service, and that they have no other agenda but to..well, spy. ÚZSI is responsible both for human and signals intelligence.
Czech Interior also runs the government's cipher service and provides many technical services for ÚZSI.