ZURICH, Sept 8 (Reuters) - The inflation outlook is more uncertain than normal and it was premature to say prices had peaked, Swiss National Bank Chairman Thomas Jordan said on Thursday, adding the SNB had not yet decided what steps to take at its policy review in two weeks.

"You cannot say we have passed the zenith and now it is certainly heading lower," he told a Finanz and Wirtschaft financial conference.

"If it comes to a power shortage situation, to a complete gas shortage in Europe, then it cannot be excluded that inflation pressure rises again. You have to be very cautious."

The SNB increased its policy rate in June by half a point to -0.25%, its first rate hike in 15 years. Its next quarterly policy assessment is due on Sept. 22.

The SNB has switched its focus from battling the safe-haven Swiss franc's appreciation to tackling the highest inflation in decades and which reached 3.5% in August.

The reading -- the seventh month in a row that inflation has risen above the SNB's 0-2% target range -- has fuelled talk that the central bank could soon tighten policy again.

Jordan declined comment on SNB currency interventions to steer the franc. He said for a long time the franc had been highly valued or overvalued, but the situation relaxed when the franc's nominal rise stopped and inflation abroad swelled far above that in Switzerland.

"At the moment it is rather so that given the inflationary pressure an appreciation of the franc tends to help rather than hurt."

(Reporting by Michael Shields; Editing by Andrew Cawthorne and Paul Carrel)