Switzerland's central bank returned to profit last year thanks to the increased value of foreign currency and gold holdings.

But it warned shareholders that the volatility of its financial results meant big payouts were not guaranteed in the future. 

The Swiss National Bank (SNB), which caused turmoil in financial markets in January with the sudden removal of a currency cap against the euro, made 38.3 billion francs in profit last year, confirming preliminary results. 

This compares with a 9.1 billion franc loss in 2013 when it was hit hard by a slump in gold prices. 

Despite the strong year, the SNB tempered expectations on future handouts to shareholders, made up largely of Switzerland's 26 cantons and the federal government. 

"In view of considerable volatility in its results, the SNB does not exclude the possibility that, in some years, profit distributions will have to be suspended completely, or can only be carried out on a reduced scale," the central bank said in its annual results statement. 

It said it was unable to make any predictions about its 2015 results. 

As announced in January, the bank will pay its shareholders 2 billion francs in 2014 dividends, after cancelling a payout for the 2013 financial year. 

The total payout is more than double what the bank had previously told shareholders to expect.