WASHINGTON — Concerned about waning economic growth, central banks in Europe and China announced measures Thursday to increase borrowing and spending by businesses and consumers, a response that was all the more striking because it was uncoordinated.

Three major central banks announced policy changes in the space of an hour. China’s central bank unexpectedly cut regulated bank lending rates for the second time in four weeks. The European Central Bank cut its benchmark interest rate to 0.75 percent, the lowest level in its 14-year history. And the Bank of England said it would expand its holdings of government bonds by about 15 percent.

The Federal Reserve announced two weeks ago that it would extend its own bond-buying program until the end of the year.

The actions again cast central bankers in the role of primary responders to the global economic malaise, aiming at the same basic target they have tried to hit repeatedly over the past six years: encouraging people and businesses to borrow and spend and to take greater risks with their investments.

But Europe is mired in a recession and a political crisis. The United States is faring somewhat better in both respects but is hardly booming. China is suffering what its government has begun to describe as a sharp economic slowdown. And policy makers have not succeeded in restoring public confidence that better days are coming.

The latest round of modest measures is unlikely to change that record, instead stoking the debate between those demanding stronger action and those convinced central banks have done all they should.

Reaction was subdued. Analysts used phrases like ‘‘helpful at the margins’’ and ‘‘it doesn’t hurt.’’ European stock markets rose in an initial burst of pleasure, then receded. US stock indexes fell early, then recovered their losses.

‘’These are not big steps; I would not expect them to have a huge effect, but I think they move in the right direction,’’ said Donald Kohn, a senior fellow at the Brookings Institution who served as the Fed’s vice chairman from 2006 to 2010. ‘‘I think it’s certainly the case that monetary policy can’t cure all the world’s ills, but I think it can do some good.’’

Fed Chairman Ben S. Bernanke and his European counterparts have tried to shift the burden of economic policy making to elected officials, urging them to bolster short-term growth by addressing long-term problems like the level of public debt and the cost of social programs. But countries have made little progress on those issues.

The European Central Bank announced a reduction in its benchmark interest rate to 0.75 percent from 1 percent, which was once regarded as an effective minimum. President Mario Draghi said he was optimistic about the long-term benefits of steps announced last week by European leaders. But for now, he said, economic problems continued to deepen.

“We see now a weakening basically of growth in the whole of the euro area, including the country or the countries that had not experienced that before,’’ Draghi said.

The Bank of England, which cut its benchmark rate to a record low of 0.5 percent in 2009 and has kept it there ever since, chose to pull on a different lever. It said it would add government securities worth $78 billion to its portfolio of $508 billion — a policy called quantitative easing — in its latest effort to jolt the struggling British economy out of a double-diprecession.