ZURICH (Reuters) - Switzerland's highest court has ruled a request from the Netherlands for information on Dutch account holders at Swiss banks is valid, overturning a lower court's decision to block the order.

Swiss banks have paid billions of dollars in fines in recent years as global prosecutors, led by the United States, chipped away at the secrecy rules that for decades enabled the world's wealthy to keep their cash in Switzerland, out of sight of the taxman.

Last year, the Netherlands said it had requested information on Dutch account holders at UBS <UBSG.S> and Credit Suisse <CSGN.S>, making use of a new bilateral agreement to crack down on tax avoidance.

But in March, the Swiss Federal Administrative Court sided with a Dutch client of UBS fighting the order, ruling the request was not covered by the information-sharing agreement since it did not include names of individuals.

The tax agency appealed, and on Monday Switzerland's Federal Supreme Court ruled the Dutch request did not require the names of clients but just needed enough information to identify account holders.

The court said the purpose of the double taxation agreement is to ensure a broad information exchange between the Netherlands and Switzerland, without encouraging so-called "fishing expeditions".

The decision will be a printed as a guideline for future cases in this area.

The Swiss Federal Tax Administration said it was "happy" with the ruling. UBS declined to comment.

(Reporting by Joshua Franklin and Angelika Gruber; Editing by Raissa Kasolowsky)