Switzerland has signed a preliminary agreement with the European Union that will make it much harder for the 28-nation bloc's citizens to evade taxes by hiding money in Swiss vaults.

The deal initialed in Brussels on Thursday envisages that both sides will start collecting bank account data on each other's citizens from 2017 and begin exchanging that information a year later.

The Swiss government said in a statement that the agreement "will make an important contribution to the prevention of tax evasion."

Switzerland has already signed an automatic information exchange agreement with Australia as part of an effort to shed its long-standing image as a haven for offshore tax cheats.

It is also working on a similar agreement with the United States.