Blocked Account

What Does Blocked Account Mean?
An account that is subject to foreign exchange controls in a country that restricts the amount of its currency that can be transferred to other countries or exchanged into other currencies. 

It can also refer to accounts that are frozen, either by the U.S. government for political reasons, or for other reasons (such as death of the account holder.)

Investopedia explains Blocked Account
A blocked account is typically more serious than a frozen account, and the implication of the term is that it is longer term in nature. Once an account in the U.S. is blocked by government mandate (such as during a time of war or distress), no funds in the account can be accessed without a specific release from the U.S. Treasury.