Apple's succession plans for CEO Steve Jobs should be revealed by the company, an influential investment firm has said.

Reuters reports that Institutional Shareholder Services (ISS) has backed calls from some Apple shareholders for the plans to be revealed.

"ISS believes that shareholders would benefit by having a report on the company's succession plans disclosed annually. Such a report would enable shareholders to judge the board on its readiness and willingness to meet the demands of succession planning based on the circumstances at that time," ISS said in a statement.

Apple has recommended that shareholders vote against these proposals at the company's annual meeting on 23 February as it believes that outling the plan would give rival companies an advantage. It does, however, insist that it has a "comprehensive" plan in place for Jobs' succession.

Jobs has been on leave from Apple since 17 January, citing medical reasons. Tim Cook, chief operating officer, has taken over Jobs' day-to-day duties.

However, the proposal from shareholders was made before the latest news about Jobs' health was revealed. A regulatory filing from Apple posted on 7 January - ten days before Jobs took leave - recommends that shareholders vote against plans to reveal the succession plan.

"The Board recommends that you vote your shares...“AGAINST” the shareholder proposal entitled “Amend the Company’s Corporate Governance Guidelines to adopt and disclose a written CEO succession planning policy” (Proposal No. 5)," the filing reads.

"Adopting Proposal No. 5 would give the Company’s competitors an unfair advantage. Proposal No. 5 would publicize the Company’s confidential objectives and plans. Giving competitors access to this information is not in the best interest of the Company or its shareholders," it continues.

Jobs' medical leave would seem to make the issue even more pertinent, though at the same time more sensitive and given ISS's comments the results of the vote on proposal number five at the annual meeting on 23 February could be very interesting.