Assets belonging to people with close ties to Nicolás Maduro are also frozen.
The purpose is to prevent the funds from being taken out of the country and to ensure that they can be returned to the Venezuelan people if it is legally established that Maduro and his relatives acquired the funds illegally.
It is not clear how much money is involved or which banks are affected. However, the decision does not affect assets belonging to members of the current government in Venezuela.
Former President Nicolás Maduro was captured by US forces on Saturday in connection with a US attack on the oil-rich country of Venezuela. He has been taken to the United States to stand trial.
Switzerland has previously imposed sanctions against Venezuela.
