Cryptocurrency exchange Coinbene, ranked 16th on CoinMarketCap by adjusted volume, has announced it is undergoing maintenance on Tuesday, March 26, as the crypto industry discusses rumors that the exchange has been hacked.

The official Twitter account of Coinbene Global, @CoinBene, has responded to a user nicknamed Crypto James, who claims that his deposits have been pending for an hour and insists the exchange has suffered a hack, as the maintenance had not been previously announced.

Coinbene’s reply to his tweet reads:

“In order to enhance the user experience, CoinBene upgraded the platform wallet on March 26, 2019. During maintenance, it will affect related operations such as deposit and withdraw, trading will not be affected.”

In another tweet, Coinbene adds that the completion time of the maintenance will be announced separately. The exchange states that all withdrawals and deposits will be completed automatically after the maintenance concludes.

However, some insiders suggest that the maintenance announcement is a cover for a large hack that might involve up to $40 million stolen. Nick Saponaro, CIO of blockchain startup Diviproject, wrote on Twitter that the massive outgoing transactions from the platform shown on major statistics website for Ethereum, Etherscan, might serve as an evidence of an attack.

In a comment to Saponaro’s tweet, Twitter user Stephen Morrison noted that the funds appear to have been moved to an address commented on as “cold wallet.”

Nick Schteringard of Russian crypto media Forklog also mentioned “strange activity” on Coinbene in his Twitter. Schteringard cites users who claim that their wallets were hacked using two addresses. He also notes that a large portion of previously unknown MaximineCoin, or MXM, is involved in transactions. MXM has seen gains of more than 700% per this month, he writes.

On March 19, the United States Securities and Exchange Commission (SEC) published a report on crypto exchanges prepared by Bitwise Asset Management, creator of a crypto index fund. In the report, experts claimed that 95 percent of Bitcoin (BTC) trading volume reported by unregulated crypto exchanges were fake.

The SEC’s Bitwise report, inter alia, mentioned Coinbene as the largest BTC exchange in the world with $480 million in daily volumes. The authors believe that their activity is suspicious, especially due to the fact that trading timesteps frequently coincide and the amounts of buying and selling are almost similar.

Cointelegraph will update this story as more information is made available.