European Central Bank's Draghi expected to underline willingness to do more stimulus if needed

The European Central Bank has kept its key interest rates on hold, leaving investors to look to comments later from President Mario Draghi for hints on any further stimulus.

Draghi will assess the state of the economy at a news conference after the bank decided Thursday to leave its main interest rate at 0.05 percent.

The rate decision was a foregone conclusion. ECB officials have said the benchmark is now so close to zero they cannot reduce it further.

Instead, attention has focused on whether the bank will start buying corporate or government bonds to boost growth and inflation in the 18 euro countries.

Large-scale bond purchases have been used by other central banks including the U.S. Federal Reserve. But the step is more complicated in a currency union.