The US Federal Reserve's Open Market Committee (FOMC) is due to release the minutes of its April meeting on 20 May and several policymakers, including Fed boss Janet Yellen are scheduled to speak later in the week.

In the statement from its April meeting, the Fed said that the US economic slowdown in the January-March first-quarter was partly transitory. As such, market watchers will be tracking the minutes to see to what degree the FOMC-members have confidence in a rebound in growth in the second-quarter.

While the exact timing of the planned increase in interest rates is largely dependent on economic data and therefore up for debate, there is unlikely to be any clear indication on the timing of the first rate hike in the minutes.

Hike in 2016?

Earlier in the day, Chicago Federal Reserve president Charles Evans, who votes on Fed policy, said the US central bank should not hike rates until early 2016.

Evans, who has long argued for a delay to rate hikes so as not to weaken economic recovery, said the Fed should not move on rates until there was greater confidence that its inflation target could be hit within one or two years, Reuters reported.

Evans, speaking in Munich, said: "Inflation is too low. The FOMC should refrain from raising the federal funds rate until there is much greater confidence that inflation one or two years ahead will be at our 2% target.

"It likely will not be appropriate to begin raising the Fed funds rate until some time in early 2016."

Societe Generale said in a note to clients: "Although the liftoff is expected to still be the first step in the normalisation process, economists would not be surprised if the FOMC shifts the blend of its two normalization tools toward slightly fewer hikes and a bit more tightening via the balance sheet."

Evans, speaking in Stockholm on 18 May, argued for rates to start rising in early 2016, but also said that the world's most powerful central bank could look at a hike in June if the American economy was strong enough to stand on its own, without stimulus.

The main interest rate, known as the federal funds rate, has been at a record low of 0.25% since December 2008.