Jean Ping, the president of the United Nations General Assembly, has warned that the impasse over Security Council enlargement is posing a significant threat to the success of next month's UN world summit.

Although many UN member states envisage some form of expansion, there is widespread disagreement as to the number of new members, the extent of their powers and the length of their tenure.

The African Union last week dealt a blow to the G4 Germany, India, Japan and Brazil when it refused to support their bid to gain permanent seats on the Council. The G4 has called for the addition of 10 new seats to the present 15-member body, including six new permanent seats without veto. China said on Sunday it would veto the G4 plan if it goes to a vote.

But Mr Ping, who is also the foreign minister of Gabon, believes it is still possible to achieve important advances on terrorism, human rights, UN management and development at the summit.

“We are in a situation which is certainly not the best to deal with drastic reform. It needs serenity to move forward,” Mr Ping told the Financial Times, in a broad-ranging interview.

Mr Ping told the FT that to delay enlargement, as some propose, would also cause problems.

“To postpone it will not be easy,” he said, warning that it could elicit a “very negative reaction by some countries”. Instead, the challenge was to foster agreement with broad support. “The role of a president is to avoid drastic confrontations. I have always tried to avoid a vote which will be divisive; I continue to think there is room for that.”

Diplomats say Mr Ping is considering a compromise that would not establish new permanent seats, which many countries oppose. Instead, he would create long-term re-electable seats, with a 10 to 12-year tenure.

Following the G4's failure to win African Union support for its plan, Kenzo Oshima, Japan's UN ambassador, suggested Tokyo could consider alternatives.

“We are not so inflexible as to discard other options. Our priority continues to be the one we have worked on,” he said, [but] “at some point, if the situation demands” the four allies could “look at other options”.

It is unclear whether Germany, India or Brazil are so open. Diplomats say India, which was reluctant to abandon the veto, is not keen on the compromise.

On the other side, countries that oppose new permanent seats suggest that even a 10-year tenure would be too long.

Meanwhile, Mr Ping and his advisers concede difficulties remain on other reforms. Calls for a new “peace-building commission” to help failed states were “broadly accepted” by member states. But the question of which countries would serve on the commission remained contentious. “Everybody wants to be on that commission,” said Mr Ping. “But the bigger the commission is, the less efficient.”

Similarly, many countries accepted the need for a new human rights council, but were not agreed on its membership. “Some countries propose 20, others propose 191. Many say, ‘Lets keep it the same number as in Geneva [53],'” he said. “I hope we could arrive at a figure which would be broadly accepted. But if it's not, we will say that the next session of the General Assembly will discuss the composition.”

All UN members condemn terrorism, but are split on how to define it. “The [outcome] document condemns any terrorist attack. I am not sure it would have been the case a few years ago,” said Mr Ping. But “the problem is the definition”. His personal opinion was that the UN could agree a comprehensive convention without one.

Copyright The Financial Times Limited 2018. All rights reserved.

Comments have not been enabled for this article.