Q - “We have noticed that there is a 64-bit AnyConnect Client on the Cisco
website and have downloaded and tried a manual install on a test
machine using Ubuntu 10.10 x64 based OS but was advised with a message
that this client is not for Debian based systems.”
This suggests that the Debian distribution of Linux that you are using is not supported hence your message.
Q – “We also noticed that the ASA fails to detect x64 linux OSs, incorrectly offering a link to download the client for Windows. Is this a known issue, and if so do you have any idea when it will be fixed?”
A – If it’s trying to detect the Debian OS then I suspect that this is why it’s not working.