Architect Hidetsugu Aneha falsified data on 21 buildings including a hotel and condominiums in Tokyo and its suburbs, according to the land ministry.

Of these, 16 have since been found to have structural flaws, a ministry official said.

"I felt pressure to cut costs," Aneha told reporters earlier as he admitted the allegations.

Some of the buildings would be at risk even at upper five on the Japanese earthquake scale, an intensity point at which heavy furniture could topple over but some people can still stand up.

News reports said the land ministry plans to file criminal complaints against Aneha and six people responsible for designing the buildings, which remain open.

Japan endures 20 percent of the world's major earthquakes and designs its buildings to withstand them, adding to construction costs in one of the world's most expensive countries.

Last year 51 people were killed and hundreds injured in a 6.8-magnitude quake in the Niigata region, 200 kilometers (125 miles) northwest of Tokyo.

Tokyo is constantly bracing for the dreaded "Big One" as the area is hit by a major earthquake about every 60 years.

The last major quake in the Tokyo area occurred in 1923, leaving 142,807 dead or unaccounted for.

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