The choice of the UN chief has for decades been the purview of the five permanent Security Council members -- Britain, China, France, Russia and the United States -- in a selection process kept mostly behind closed doors.

But a UN resolution adopted by the General Assembly in September lifted some of the secrecy surrounding the process, asking candidates to present their resumes and lay out their vision for the job.

"This fires the starting gun to be the next secretary-general," British Ambassador Matthew Rycroft said of the letter sent to all 193 countries of the United Nations.

The letter calls for "candidates to be presented with proven leadership and managerial abilities, extensive experience in international relations and strong diplomatic, communication and multilingual skills."

Following weeks of negotiations, notably with Russia, the letter was signed by US Ambassador Samantha Power, this month`s president of the Security Council, and Mogens Lykketoft, president of the General Assembly.

Russia had bristled at references to a specific timetable giving candidates until the spring to come forward and was cool to suggestions that women should be strongly encouraged to apply.

The letter states that "early presentation of candidates will help the council`s deliberations" and that the selection process will begin by the end of July.

It calls for "women, as well as men" to enter the race and states that hearings can be held to allow candidates to make their pitch, although participation in these meetings is not mandatory.

Lykketoft said the first hearings of candidates will take place in late March and early April, allowing member-states to ask questions about their priorities.

The UN`s next secretary-general will take up the post on January 1, 2017, replacing Ban Ki-moon who held the job for two five-year terms.

Time for a woman?

Speculation surrounding the next UN chief has focussed on whether the first woman will take up the job, after eight men in the job, and on picking a candidate from Eastern Europe.

Russia has said that the next UN chief should come from that region, the only one that has yet to be represented in the top job.

Despite moves to open up the race for the first time in the UN`s 70-year history, the Security Council will submit only one name to the General Assembly for endorsement as the next secretary-general.

Still, the "1 for 7 billion" campaign of NGOs lobbying for more transparency welcomed the letter as "ground-breaking", marking the start of the official process for the top post.

"We must start a global conversation about what type of person we want in the hot seat, and what we want them to do when they get there," said Natalie Samarasinghe, a campaign member.

Among the names being floated for the top job are two Bulgarians -- UNESCO chief Irina Bokova and EU budget commissioner Kristalina Georgieva -- along with Croatian Foreign Minister Vesna Pusic.

Among non-Eastern Europeans, attention has focused on former New Zealand prime minister Helen Clark, who now heads the UN Development Program, and Chilean President Michelle Bachelet.

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