Retirement of SNB's Danthine sparks succession search

* SNB vice-chairman Danthine to retire in June 2015

* Sparks search for new third SNB board member

* News (Other OTC: NWSAL - news) comes as SNB faces renewed pressure on franc

* SNB next meets for rate decision on Sept. 18 (Adds detail)

By Joshua Franklin

ZURICH, Sept 5 (Reuters) - The Swiss National Bank said on Friday its vice-chairman Jean-Pierre Danthine - who helped introduce a cap on the value of the Swiss franc - will retire in June, launching a succession search as the SNB faces renewed pressure on the franc.

Danthine was given the task of implementing the minimum exchange rate when it was first introduced in September 2011. Since 2012 he has been responsible for financial stability which includes overseeing Switzerland's too-big-to-fail laws.

The SNB said in a statement that Danthine would step down upon reaching retirement age as well as the end of his term.

His departure is the biggest news out of the SNB in a week where the Swiss franc has hovered perilously above the 1.20 franc per euro threshold imposed by the central bank. Concerns over Ukraine have drawn investors to the traditional safe-haven currency and the European Central Bank's latest stimulus measures have weakened the euro, keeping pressure on the franc cap ahead of the SNB's next rate decision on Sept. 18.

A spokesman for SNB said the central bank will start looking for a replacement to Danthine fairly soon and that any successor would likely be from French-speaking western Switzerland, in an unspoken policy of preventing an all-German-speaking board. The other two members, Thomas Jordan and Fritz Zurbruegg, have German as their mother tongues.

This would likely rule out any of the three department deputies, positions which have often paved the way to the governing board itself.

In a statement, the bank praised Danthine's "strong commitment to a stability-oriented monetary policy" during his term which ends in June 2015, close to his 65th birthday in May.

Danthine's departure will likely mean Zurbruegg, who joined the SNB in 2012, will become vice-chairman as the governing board's second most senior member.

MARKET REACTION

In the immediate aftermath of the announcement, the franc strengthened to session-highs against the euro but has since weakened to trade within the day's range.

The SNB stands ready to intervene in the foreign exchange market to defend its cap on the franc and could take further measures to ensure price stability, its chairman told a newspaper last week.

The three-person SNB board sets monetary policy and oversees the franc cap. Each of the three oversees a department at the bank; one focusing on international affairs, another on financial stability, and one on operational issues.

Swiss law states that board members must be Swiss, live in the country and have a "flawless reputation and a stated knowledge of currency, bank and financial questions". The government elects them for six years, though Danthine will serve five years of a six-year term.

This is the first regular replacement of an SNB board member since Danthine joined in January 2010. The most recent rotation in 2012 was sparked by previous SNB Chairman Philipp Hildebrand quitting after his wife made a currency trade weeks before the SNB set its cap on the franc's value. (Additonal reporting by Oliver Hirt and Katharina Bart; Editing by Ruth Pitchford and Dominic Evans)