CHICAGO - Swiss National Bank Vice Chairman Phillip Hildebrand said on Friday that the bank would do whatever it takes to adjust monetary policy -- but only when the right time comes.

Hildebrand, taking questions from the audience after a speech at a Chicago Federal Reserve/World Bank conference, said the policy reversal would be driven by the evolution of inflation rates.

The SNB is not in a hurry to draw down the portfolio of assets bought to stabilize the nation's economy and financial system, Hildebrand said.

Some of the assets are now trading at a profit, but a sale of the profitable portion, while politically popular, would leave the portfolio weighted too heavily with poor-quality paper, he said.

It could potentially be a long time (before an exit), he said. It's a diversified portfolio. That's the way we went into it. Our strategy was not to maximize this for a purely commercial purpose. It is for stabilization.

Earlier this week, the policymaker termed the Swiss economy still fragile despite some encouraging signs.

Although the SNB has pledged to fight any rise in the Swiss franc against the euro and to buy bonds if needed, the SNB objective was not to weaken the currency or gain a beggar thy neighbor advantage, Hildebrand said. (Reporting by Ros Krasny; editng by Carol Bishopric)