United Nations formally kicks off race for next secretary-general

The United Nations formally kicked off the race for the next secretary-general on Tuesday

and the world body's 193 members were encouraged to consider putting forward a woman for the top job that has been held by a man for the past 70 years.

U.N. Secretary-General Ban Ki-moon, a former South Korean foreign minister, is due to step down at the end of 2016 after serving two five-year terms. In a bid to boost transparency, the presidents of the Security Council and the General Assembly - U.S. Ambassador Samantha Power and Mogens Lykketoft of Denmark - sent a letter on Tuesday to U.N. member states to begin the search for Ban's replacement by outlining the process and soliciting candidates.

"Convinced of the need to guarantee equal opportunities for women and men in gaining access to senior decision-making positions, Member States are encouraged to consider presenting women, as well as men, as candidates," they wrote.

Lykketoft said so far two candidates had been put forward for selection - former U.N. General Assembly President Srgjan Kerim of Macedonia and Croatian Foreign Minister Vesna Pusic.

"We invite candidates to be presented with proven leadership and managerial abilities, extensive experience in international relations and strong diplomatic, communication and multilingual skills," said Power and Lykketoft in the letter.

They asked states to present candidates to them in a letter, which would then be circulated to the 193 U.N. members.