The African Union was expected to introduce counter-proposals after Brazil, Japan, Germany and India - known as the Group of Four - sought to win the support of the UN General Assembly in their bid to join the Security Council as permanent members.
But with no consensus emerging over enlarging the 15-member council, the African proposals risk further delaying a solution to an issue that has taken 12 years to come to a vote.
Brazil tabled a draft resolution on Monday, which called for an expansion of the council from 15 to 25 members, including six new permanent seats.
Under the plan, Africa would have two of the six permanent seats. The bitter debate on the draft resolution prompted Mr Annan to urge nations to "calm down."
The African proposals call for an additional non-permanent seat to be held by an African country, and for all new permanent members to hold veto power. The Group of Four needs thesupport of the 53 African states to reach the two-thirds necessary in the 191-nation General Assembly.Reuse content