UPDATE (6th January 14:55 BST): Cryptsy has removed the advisory from its main page and trading has reportedly recommenced.

Cryptsy, the digital currency exchange that has been dogged by rumors of insolvency amid persistent issues related to user withdrawals, has said that it has suspended its trade engine.

"Trade engine and withdrawals paused while we investigate cause of lag. Your patience is appreciated. Thank you," a message on the main Cryptsy page read at press time.

The exchange, which specializes in the trading of alternative cryptocurrencies (altcoins), has long been the subject of controversy. The exchange reported roughly 235 BTC in volume over the past 24 hours, but has long faced criticism over issues involving the withdrawal of user funds

Posts on social media and emails provided to CoinDesk provide evidence that some users have had issues taking their money out of the exchange since this fall. The continued issues – and what some users say is a lack of clarity from the exchange’s management team – have prompted claims that the exchange is insolvent or is the target of regulatory scrutiny.

The withdrawal complaints have prompted popular altcoin pricing site CoinMarketCap to delist the exchange, a move it also attributed to "skewed" prices on the platform. The site stated on Twitter that it would add Cryptsy after the issues are resolved.

In the past, Cryptsy has attributed the problems to technical issues, as well as denial-of-service attacks.

The problems have elicited comparisons to Mt Gox, the now-defunct Japan-based bitcoin exchange that, prior to its collapse, blamed technical problems for withdrawal problems and ultimately cut off access to customer funds.

Cryptsy did not immediately respond to a request for comment.

Shut-off valve image via Shutterstock