Sadly a friend of mine was told about this exchange by a another "friend" so he invested a significant amount of money. Now that he wishes to withdraw it, they told him he needs to invest a minimum amount before they allow withdrawals, so he put more in. Then they say he needs to add another large amount for taxes before he can withdraw.
It might be good if you will create a thread on the scam accusation board once you have valid proof to warn newbies that might fall into their trap.
Sad to say your friend has been scammed, don't put more investment to increase the amount, accept your loss and try to spread awareness of that scam exchange.
This might be under the HYIP category scam.
Most commonly they promise high returns or guarantee money back with little to no risk, but in reality, they're designed to take money from unsuspecting victims and disappear with the funds.
Just move on I think and learn from this costly mistake.