AOL UK has ceased development of AOL 5.0 – its browser for Mac OS X – despite previous assurances from the company of its support for Apple's Unix-based OS.

AOL released a beta version of AOL 5.0 earlier this year, but this has hit developmental problems, calling the project into question. In a recent email sent to UK beta testers, the company revealed it had ceased development of its browser for OS X.

AOL UK's chief communications officer, Matt Peacock, said: "It's not possible for us to justify the considerable investment required to create a new localized version of our browser for a niche market platform such as OS X."

Last week Apple and AOL jointly announced AirPort 2.0, which offers out-of-the-box support for AOL users in the US. Peacock said: "I must stress that we still support the Mac. Existing AOL clients will be supported indefinitely on Mac operating systems already supported by us.

Base bawl "The problem we have is the lack of an installed base at this time." Peacock added: "This decision is not set in stone. We will evaluate the development of the Mac OS X market closely, and, as the user base grows, we may choose to develop for it once again."

Apple and AOL have a history almost as old as the Internet itself. AOL introduced online services for Mac users in October 1989, supporting the Macintosh and Apple II - it didn't begin supporting IBM compatible computers for another two years, and a Windows version didn't appear until 1993. In 1995, Apple purchased two million shares of AOL stock for $12.5 million - 5.1 per cent of AOL. The company sold these shares in 1996 at a profit of $39 million.

In 1992, Apple began paying a royalty to AOL, guaranteeing $15 million over five years for the latter to get Macintosh users online. At that time, Apple's chief counsel said the deal would give AOL the funding and visibility it needed to be successful. The result was eWorld, introduced in 1995 - and closed in 1996.

Peacock stressed AOL UK's position: "AOL is organized into separate, country-level business units operating independently of each other. However, we are a mass-market company - in the UK the vast majority of AOL users don't use Macs. If Mac OS X is more widely adopted, if its installed user-base grows, then it becomes economic for us to develop for the platform."

Peacock continued: "The key thing is that we watch the market very carefully, and speak with everybody all the time. Apple fully understands where we're coming from on this."

Peacock dismissed the notion that AOL UK's decision is connected with Apple's recent deal with ISP Demon Internet, which offers UK Mac buyers out-of-the-box Internet access from the ISP.

"That's not the case at all", he stressed. "Mac users will wonder why we're doing this. The simple message is that we remain committed to the platform and will be constantly revaluating our decision based on the market's future development. This is something Mac users have to understand."