“Negotiators are also concerned about the succession law should Mugabe die or retire before the adoption of a new constitution, which is still being negotiated,” the African National Congress (ANC) said on its website.

The 87-year-old leader has travelled to Singapore at least four times this year for medical attention, although he denies reports that he may be in a poor state of health.

The veteran leader, in power since 1980, is locked in a power-share government with his former rival, Prime Minister Morgan Tsvangirai.

The 2008 deal brokered by regional leaders included requirements for a new constitution and amended media and election laws before new polls are held.

But public consultations on a new constitution have been repeatedly postponed after outbreaks of violence, mainly blamed on the supporters of Mugabe’s ZANU-PF.

Since its formation, the unity government has been marred by disagreements and boycotts, with Mugabe last year suggesting that elections be held to dissolve the deal.

Tsvangirai has said that elections were not possible before reforms were in place.

Last month a senior member from Mugabe’s party said the country could see polls at least in 2013, but others in his party continue to insist on polls later this year, in an unusually public show of dissent within the ranks.