(Reuters) -- Vice President Joe Biden warned on Monday that there is no way that China will be able to sustain its current level of economic growth because of what he called its God-awful one-child policy.

Biden, who will help host Chinese Vice President Xi Jinping in Washington next week, said that when he visited China in August, he made clear to Beijing that the United States' fiscal problems were surmountable, and less significant than China's stood to be.

When you talk about, we have a problem with our entitlement programs, we are going to be able to handle that, but by God, thank God we don't have your problem, Biden said, recalling the trip that followed the U.S. debt ceiling crisis and credit downgrade by Standard & Poor's.

Because of that God-awful one-child policy they have, what happens now is in the next 20 years they're going to have such an inverse proportion of the number of people working to the number of people retired that there is no way they can sustain that growth, he said.

China introduced its one-child policy in 1979 to limit births in the world's most populous nation. It has relaxed the rules somewhat in the past few years and some couples are now allowed to have a second child.

Biden's apparently unscripted remarks, which came during a speech about college affordability in Florida, could cast a shadow over next week's visit to the United States by Xi, who is expected to succeed Chinese President Hu Jintao next year.

Biden, a former U.S. senator with deep experience in foreign policy, has a reputation for speaking off the cuff.

He also said, I've been sort of given part of the China portfolio here, an apparent reference to reports that President Barack Obama has given him an expanded role in the U.S. policy toward China.

In his remarks in Florida, Biden was trying to make the case that the United States remains the world's largest economy and is better positioned than any other country in the world to lead the 21st century.

At the same time, he made clear he was not cheering for slower Chinese economic growth.

I really want to see China continue to grow. Don't let the fact that we are 2-1/2 times as large as your economy in any way dissuade you from continuing to work hard, he said.