The European Central Bank (ECB) caused no surprise on its return from its first-ever summer recess and left key interest rates in the euro zone on hold, even in the face of an acceleration in one of the bank's preferred indicators of future inflationary trends, M3 money supply.

But what did take central bank watchers by surprise was the fact that the ECB chose to release fresh M3 money supply data at exactly the same time. And the figures pointed to a pickup in growth of the broad money indicator in July, which, at a first glance, is not exactly good news for inflationary trends in the medium term.

It was that sort of trend that ECB president, Mr Wim Duisenberg, had said a month ago the bank would be looking out for in a possible reassessment of monetary policy for the euro area.

If the trend continues in coming months, the chances could increase that the ECB will tighten monetary conditions in order to prevent an upward inflation spiral.