Samsung Electronics Co. suffered another blow to its efforts to cut the dependency of its smartphone business on Google Inc.’s Android operating system, postponing the launch of a new model that runs on its own Tizen software.

The news is the latest disappointment for the Korean giant which is trying to defend its position as the world’s largest maker of smartphones from the twin challenges of Apple Inc. AAPL and, at the other end of the market range, Chinese companies such as Huawei, ZTE and Xiaomi.

Samsung SSNLF had been on track to debut the Tizen in Russia sometime in the third quarter, but said Monday it needed more time to “further enhance (the) Tizen ecosystem”, confirming word of mouth from a developers’ conference two weeks ago.

It didn’t give any details about what precisely needed to be defined or how long the delay would be, but the reference to the ‘Tizen ecosystem’ hinted at fresh concerns over the availability of apps and related services that are needed to make the product sell.

Such concerns were, in part, behind the decisions of network operators NTT DoCoMo and France’s Orange SA to pull out of promotional campaigns launching the Tizen phone.

Samsung has already launched Tizen-driven smartwatches and cameras, but is desperate to extend it to smartphones in order to gain more control over the end-user experience in its most important products. Its license agreement with Google GOOG restricts its freedom to make more than cosmetic changes to the Android system.