Swiss banking giant UBS's net profit slid by 54 percent to 827 million Swiss francs (688 million euros, $910 million) in the first quarter of 2012, significantly below expectations, it said on Wednesday.

The company was in particular hit by an exceptional charge of 1.2 billion francs on its debt, it said a statement.

In February UBS had forecast a tough first quarter due to the economic crisis when it posted its results for 2011, with net profit sliding 44 percent year on year to 4.2 billion Swiss francs.