Nokia is in the process of buying Psion's 31 percent stake in Symbian, which would give the Finnish mobile giant ownership of 63 percent of the business. Ericsson is determined not to allow Nokia to win such control.
"If Nokia had more than 50 percent of Symbian, then this would make it [the Symbian operating system] too much of a Nokia product," an Ericsson spokesman told ZDNet UK on Monday.
Earlier this month, Psion's shareholders voted in favour of the sale of its stake to Nokia. However, other Symbian shareholders can now step in and buy part of the Psion stake themselves under the terms of their pre-emption rights.
"If all the shareholders were to exercise their pre-emption rights, Nokia's stake would only increase to 48 percent," the Ericsson spokesman added.
Nokia is already the largest Symbian shareholder with a 32.2 percent stake, compared to Ericsson with 17.5 percent. Panasonic, Samsung, Siemens and Sony-Ericsson all have smaller stakes. In theory, any single player would need a 70 percent stake before it would have genuine control of Symbian -- leading to speculation that other shareholders may soon cash in by selling out to Nokia.
Ericsson refused to comment on what discussions it is already having with these other shareholders, but it seems unlikely that it can persuade them all to up their stakes.
Siemens has already announced that it has no plans to exercise pre-emption rights on Psion's Symbian stake. A company spokesman said last month that Siemens sees no need to increase its holding in Symbian as it already has access to the operating system source code, adding that Nokia's move has "no impact" on its strategy.