Since early 2014 Slovenia has lobbied for Türk, leveraging the diplomatic network as well as visits abroad to promote his candidacy. Now the Foreign Ministry will file the formal candidacy with the UN, the government said.

The election will be held in 2016 and according to informal UN rules the Eastern European bloc is seen as next in line to produce the secretary general, who will succeed incumbent Ban Ki-moon in 2017.

Accordingly, several countries have endorsed their candidates, with Croatia promoting Vesna Pusić, the outgoing foreign minister, Bulgaria the UNESCO Secretary General Irina Bokova, and Macedonia Srgjan Kerim, a former chair of the UN General Assembly.

"Türk is often mentioned as a credible candidate for secretary general who enjoys a high degree of international reputation...A successful candidacy would be of extraordinary importance to Slovenia," the government's press release reads.

Türk said he was honoured by the government's decision, which he accepted with "a deep sense of responsibility". He said the decision was based on consultations conducted over the past two years.

"The consultations took into consideration my experience of more than 30 years of working with the UN and showed unquestionable credibility of the bid, as well as its chance of success," Türk stated in a written response. He pledged to do everything in his power in the coming months to justify the trust put into him.

"I would here like to express my wish for understanding and support of the broadest possible group of people in Slovenia and its political powers. Slovenia needs being open to the world and can contribute a lot to today's world."

The former president is no stranger to the UN, having acted as the Slovenian permanent representative between 1992 and 2000 and as assistant secretary general between 2000 and 2005 to Kofi Annan. He was elected the president of Slovenia in 2007, serving a five-year term.