Morgan Stanley has delayed upgrading to BlackBerry 10, as concerns mount over the long-term stability of the phone vendor.

Morgan Stanley would usually now have firm plans in place to roll out the latest BlackBerry devices, according to sources close to Bloomberg, but has decided to hold off spending on the newest smartphones and operating system as the phone company considers its future.

The bank is said to be concerned that the sale of the Canadian firm would mean the BlackBerry 10 platform may not be supported in the long term. The bank, which has over 55,000 employees, will instead continue to use its BlackBerry 7 handsets, handed out to employees across its organisation in 2011.

Despite some enterprise customer wins, BlackBerry has struggled following the launch of its Z10 and Q10 devices, failing to win over customers as the vendor attempts to regain share of the smartphone market from the likes of Apple and Samsung. In its latest quarterly results, BlackBerry shipped 2.7 million devices running the new BlackBerry 10 operating system, as part of a total of 6.8 milllion phones sold, a figure which analysts have labelled disappointing. The company also incurred a $84 million (£53 million) loss over the period.

BlackBerry's board of directors has now formed a committee to explore strategic alternatives for the firm's future, which could involve joint ventures, or even the sale of the company.