The European Central Bank is in no rush to change the rules of its bond-buying programme because they serve a purpose and the ECB can still "go quite a long time" without violating them, its chief economist said on Wednesday.

"We think we can go quite a long time and buy and respect the principles...in terms of the mix of what we buy," Philip Lane told an event in Washington.

"There is a value to the current limits, they were put in place for a good reason. And if we hit a conflict, where the limit conflicts with the delivery of the inflation target, then we have to see what we can do."