AppleInsider reports that Apple is working on bring back the ability to backup using Time Machine to a hard drive connected to an Airport Extreme base station.

The feature which was widely touted prior to Leopard’s release was pulled at the last minute with all mention of it being removed from Apple’s website.

According to a person familiar with Leopard’s ongoing development, Apple is internally classifying the inability to select an AirPort Disk under Time Machine as a known issue. The matter is documented under a unique “Bug ID” number and titled: “Cannot set Time Machine Backup to AirPort Disk.”

In the bug report Apple notes that the issue is “currently being investigated by engineering.”

The feature is widely expected to return in an upcoming update to Mac OS X 10.5 Leopard which is well under development.