Cryptocurrency exchange BTC-e is still inaccessible after “unplanned” maintenance took its website offline yesterday.

The Russia-based trading platform has so far provided only sporadic information about the problem, which appears to be unforeseen and affects its “data center.”

Our engineers are still looking into the issue in data center. We hope to get back online soon. Will continue to keep you updated #btce — BTC-E (@btcecom) July 25, 2017

The latest English language tweet from BTC-e states it is “continuing to perform” maintenance and will “keep (users) updated.”

Five hours previously, a Russian update had said that the work was “nearing completion.”

Theories as to why the exchange suddenly went offline have already turned to a potential funds compromise.

66,000 Bitcoins out

On Twitter and Reddit, commentators produced a timeline involving the movement of 66,000 Bitcoins out of a cold storage wallet hours before the outage.

“And while BTC-e is ‘down,’ some $169 mln Bitcoin fortune is on it's (sic) laundering way via hundreds of wallets,” an accompanying description announced.

And while BTC-E is "down", some $169M bitcoin fortune is on it's laundering way via hundreds of wallets, cur pos:https://t.co/yH0irtyJqb pic.twitter.com/gjknwI33G7 — Liveuamap (@Liveuamap) July 25, 2017

BTC-e is not the only major exchange to face problems recently. Coinbase, the US’ largest exchange, has suffered frequent downtime lasting several hours as its technical apparatus struggled to cope with increased demand.

Cointelegraph reminds readers to store their coins offline in a cold storage wallet over which they have full control. Never leave your cryptocurrency holdings on an exchange or under the control of other third parties.