About 22.4 percent of all homes in urban areas, or 48.98 million units, were lying vacant in China in 2013, according to China Business News on Wednesday citing a report released by a college research center.

The vacancy rate was 1.8 percentage points higher than that of 2011, according to the Research Center for China Household Finance Survey under Southwestern University of Finance and Economics that released the study.

Chongqing municipality, one of the six cities studied by the university, had the highest vacancy rate of 25.6 percent, 7.1 percentage points higher than Shanghai, which had the lowest rate, 18.5 percent. Beijing recorded 19.5 percent vacant homes in the same period.

The figures remain controversial, however, since it is widely considered difficult to asses how many of homes are actually vacant as the country's statistical authorities have yet to provide latest data, said the newspaper citing industry insiders.

"The survey is quite significant, though," it added.

These 48.98 million vacant homes, particularly commercial and affordable housing units, can meet the whole demand for housing in China, especially when the total requirement is for 32.5 million units at most, the report said.

Statistics from the report show that more than 89.2 percent of urban residents have their own rooftop, of which 21 percent have more than one home.

Vacant apartments, left unoccupied either because home owners have migrated to other cities or because they have more than one unit (but are unwilling to give them on rent), can translate to as much as 4.2 trillion yuan mortgage home loans, said the newspaper citing Gan Li, director of the research center.

It's a huge waste of money that largely undercuts the financial efficiency in the country, Gan said.