SNB can keep FX cap for years: government official

* SNB has cap of 1.20/euro since last September

* Gaillard: cap could hold for years 'if required'

* Cites lack of euro zone unity on future vision

* Expects weak growth over next 12 months

ZURICH, Aug 13 (Reuters) - The Swiss National Bank could hold its cap on the Swiss franc's value for years if necessary, a senior government official was quoted as saying on Monday, nearly a year after the bank set the barrier saying the euro crisis could trigger a Swiss recession.

The central bank set the cap of 1.20 francs per euro last September after investors seeking a haven from the euro zone poured into the franc, sending the currency to record highs and ero ding the competitiveness of Sw iss exports and tourism.

Asked by the Tages-Anzeiger newspaper how long the SNB would be able to maintain its cap on the euro, official Serge Gaillard said: "If required: years. But of course we hope that the franc will weaken once more and that the exchange rate will normalise."

Gaillard, who holds a top job at the state secretariat for economics (SECO), will take over the federal finance administration on Oct. 1 after the previous head Fritz Zurbruegg joined the SNB's governing board on Aug. 1.

The Swiss economy has continued to grow despite the three-year-old debt crisis that has now spread to Italy and Spain, the euro zone's third and fourth biggest member states, and is crushing the confidence and spending power of European businesses and households.

Investors complain that euro leaders are taking too long to agree on plans for closer political integration that might boost confidence in the shared currency and in the bloc's weaker sovereign debtors.

"There is no unity on what economic and stability policy for the whole euro zone should look like," Gaillard said. "However, if this dissent is remedied, Europe has potential to grow again."

Asked if until then the situation would remain difficult for Switzerland, he replied "yes", saying nervousness on the markets means that for the time being the cap must be defended.

The IMF has said Switzerland should allow its currency to trade freely once deflationary pressures ease and growth picks up.

Switzerland's economy has so far staved off the worst effects of franc strength, with stronger-than-expected economic growth of 2. 0 p e rcent year-on-year in the first three months of 2012 whi le the jobless rate held at 2.7 percent in July. G ross domestic product data for the second quarter is due on Sept. 4.

However, Gaillard said he expects only weak Swiss growth and a slight rise in unemployment over the next 12 months. "We will arguably have to say goodbye to the strong (economic) growth rates of the last seven to ten years," he added.