The online platform crypto.com suspended customer withdrawals for about 14 hours on Monday, after reports of unauthorized activity in the accounts of some users, the company said.

No user funds were lost, Chief Executive Kris Marszalek said on Twitter late on Monday. While he didn’t offer details of the incident, he said the company will offer a full report after it completes an investigation.

“Our...

The online platform crypto.com suspended customer withdrawals for about 14 hours on Monday, after reports of unauthorized activity in the accounts of some users, the company said.

No user funds were lost, Chief Executive Kris Marszalek said on Twitter late on Monday. While he didn’t offer details of the incident, he said the company will offer a full report after it completes an investigation.

“Our team has hardened the infrastructure in response to the incident,” he said.

Late on Sunday night, the Singapore-based platform said via Twitter that it had a “small number of users reporting suspicious activity on their accounts” and that it would in response halt all withdrawals.

The company wasn’t immediately available for comment on the details of the incident.

Crypto.com has become one of the larger cryptocurrency platforms, currently ranked 10th in spot trading, according to CoinMarketCap, and the company has become far more visible in recent months.

It has struck a number of sports-related marketing agreements recently. In November, it signed a $700 million, 20-year naming-rights agreement to Los Angeles’ Staples Center, home to the NBA’s Lakers.

In February, it will run a Super Bowl ad, its first. It has already launched an ad campaign that features the actor Matt Damon.

Malicious activity is a small but persistent part of the crypto markets. Unlike credit-card transactions, transactions for bitcoin and other digital assets are nonreversible, given the nature of the technology.

About $3.2 billion worth of cryptocurrency was stolen in 2021, according to analytics firm Chainalysis, up 516% from the year before. Most of that, about $2.2 billion, was stolen from decentralized platforms, ones that operate without any single ownership group. The amount stolen from centralized platforms was less than $500 million.

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Write to Paul Vigna at paul.vigna@wsj.com