Nearly one in 10 European households has invested in cryptoassets, an ECB study published Tuesday said, highlighting high demand for the risky investments.

"As many as 10 percent" of survey respondents in six large eurozone countries, including Belgium, Germany, Spain, France, Italy and the Netherlands, said they owned cryptoassets.

The proportion of crypto owners varied between the countries, with the figure as low as six percent in France and above 14 percent in the Netherlands.

Financial oversight bodies have been increasing their scrutiny of the crypto market as the asset class has grown, while recent volatility has highlighted the risks involved for investors.

Interest rate hikes in the United States and the Russian invasion of Ukraine provided the backdrop for steep drops in the price of bitcoin and other crypto assets.

Cryptocurrency "is worth nothing", European Central Bank President Christine Lagarde said in the Netherlands on Sunday.

"It's based on nothing. There is no underlying asset to act as an anchor of safety," she said, counselling potential investors not to follow "hype".

The majority of holdings were worth "less than 5,000 euros" ($5,358), the report said, with the tendency towards smaller stashes.

High- and low-income households were relatively more likely to hold crypto than middle-income households.

"On average, young adult males and highly educated respondents were more likely to invest," the report said.

An increasing number of institutional investors were also involved in the risky asset category, with 56 percent of those surveyed saying they had some exposure, up from 45 percent in 2020.

The total size of the crypto market reached a high of over 2.5 trillion euros "in late 2021" and was still "seven times bigger than it was at the start of 2020" despite recent drops, the report said.