Apple is said to be in the final stages of testing a new line of iMacs with higher-resolution Retina displays.

The next-gen computers will sport a slimmer profile than the current model and pack faster processors and improved WiFi antennas, Digital Spy said citing 9to5Mac.

Code contained in the OS X Yosemite beta offers a hint at what resolution the new iMacs are likely to be, with the operating system supporting 6400 x 3600, 5760 x 3240 and 4096 x 2304.

Several Apple product lines are due for a refresh, and the company is expected to announce new iPad hardware and a release date for OS X Yosemite at a press conference next month.

Recent reports suggest that the firm also is planning to refresh its Mac Mini range at the event, so we may see more than one new Mac debut alongside the new iPads.

Rumours suggest that the iPad event will be held on October 21, but this date remains unconfirmed.