* Japan, euro zone performing better than expected
* China growth expected to be slower - Obstfeld
* Hard to say what will happen with U.S. fiscal policy
LONDON, May 26 (Reuters) - The dip in the U.S. economy is a "splutter" rather than a more serious downturn, the International Monetary Fund's chief economist said, though policy uncertainty in Washington was making forecasting increasingly difficult.
In an interview with Reuters, Maurice Obstfeld, who is nearing his two-year anniversary as the IMF's top forecaster, said China's economy was also slowing, though both the euro zone and Japan were performing better than expected.
The Fund's last set of forecasts in mid April nudged up its global growth projections to 3.5 percent for this year and 3.6 percent for next year.
Since then, however, there have been some shifts in the landscape.
A string of controversies surrounding U.S. President Donald Trump's administration have put his plans to cut taxes and increase infrastructure spending on the back-burner, taking some of the steam out of the world's top economy in the process.
Revised first quarter U.S. GDP numbers due later are expected to confirm it grew at less than 1 percent.
"We saw the weak first quarter in the U.S that we interpret as a splutter rather than a change in the fundamental trajectory of the U.S. economy ... A soft patch in other words," Obstfeld said on the sidelines of a City Week conference on Thursday.
"And in the second quarter we have seen China taking some pretty energetic measures to slowdown credit growth and get a better grip on what is going on in the shadow banking sector.
"That seems to have taken some of the froth out of the economy. So we see a bit of slower growth there."
It is too early to say for sure whether the two factors would see the IMF lower it next set of global forecasts in July.
The process is not yet in full swing, but the task is also being made more complicated than normal by a lack of clarity and mixed messages over U.S. policy.
Obstfeld said that while there was now a rough outline of what maybe Trump would like to do, Paul Ryan, one of the other most senior members of the Republican party, seemed to have a different views.
"It's hard to say what exactly will happen and what the macro impact will be," Obstfeld said. "We are working to find out what is the most likely scenario and what impact that will have on growth and our forecasts."
"We don't know when or what the fiscal initiative will be so I think markets are kind of looking at this and saying show us the money."
There have been upside surprises since April, however, that are helping balance some of the U.S. and Chinese loss of momentum.
A weaker dollar and lower bond yields was a potential boost for emerging markets and other global borrowers.
Japan is performing better than already raised expectations as is the euro zone, which this month saw France elect pro-business Emmanuel Macron over the anti-euro Marine Le Pen and is being driven by a humming German economy.
"If you look at the soft indicators, PMIs, even in France where the hard indicators have not been amazing, you get some hint there might be an upside surprise," Obstfeld said.
The strengthening euro zone recovery has also fuelled talk that the European Central Bank will cut its stimulus programme again by the end of the year. The IMF, as usual, though is urging it to take things slowly.
Asked whether it would be wise to tread carefully with stimulus removal, he said: "That would be my view." The recent U.S. "soft patch" also meant that the Fed does not need to be overly aggressive as it raises interest rates, the next of which is expected next month.
"In view of the weak first quarter and the fact wage growth is still low, I don't think they feel a huge danger they are going to get behind the curve," Obstfeld said
"I don't think they are wedded to any particular number of rate increases this year, two versus three, for example." (Reporting by Marc Jones; Editing by Alison Williams)