Most American economists expect the Federal Reserve to raise interest rates once more in December and begin unwinding its 4.5 trillion U.S. dollars balance sheet in September, according to a survey conducted by the Wall Street Journal on Thursday.

Economists also expect the U.S. central bank to raise interest rates three times in 2018, a view that matches the Fed's own projections. "Labor market strength and continued economic growth will keep the Fed on course with gradual rate hikes," said Scott Anderson, chief economist at Bank of the West.

On Wednesday, Chicago Fed leader Charles Evans said the central bank could hold off on raising rates at the September meeting and instead begin winding down its balance sheet.

The Fed in June raised the benchmark interest rates for the fourth time since December 2015 and unveiled a plan to trim its holdings of U.S. Treasury bonds and other mortgage-backed securities later this year.

The Fed's balance sheet has ballooned to around 4.5 trillion U.S. dollars following three rounds of quantitative easing programs to withstand the impact of the 2008 global financial crisis.