Dutch staffing company Randstad Holding NV (RAND.AE) said Friday it has started contingency planning in case of a possible breakup of the euro zone.

"We're looking at the consequences of when we don't have the euro anymore and have to pay back in [Italian] lire and [Greek] drachmae," Chief Financial Officier Robert-Jan van de Kraats said during an analyst conference.

Randstad joins a growing number of companies that are saying publicly they are preparing for a possible breakup of the euro zone. The U.K. government has also started contingency planning to make sure it is ready to handle a collapse.

Van de Kraats said Randstad has adjusted "the selection of banks" it does business with, and added that preparations are ongoing and that the company "hasn't dealt with it completely."

He noted that the majority of Randstad's business is in the stronger euro-zone countries. Randstad, the world's largest staffing company in sales after Switzerland's Adecco SA (ADEN.VX), generates the bulk of its revenue in the Netherlands, Germany and France. The company also has operations in Italy, Spain, Portugal and Greece.

Earlier Friday, the chief executives of some of the biggest corporations in the Netherlands called on European leaders to fight the debt crisis in the currency bloc.

"It's one minute to 12 and therefore most important that there will be active measures to fight the euro crisis as soon as possible," they wrote in a letter published in Dutch paper Financieele Dagblad.

The letter was signed by the CEOs of Royal Philips NV (PHIA.AE), Unilever NV (UNA.AE), Royal DSM NV (DSM.AE), Royal Dutch Shell PLC (RDSB.LN) and Akzo Nobel NV (AKZA.AE).

-By Maarten van Tartwijk, Dow Jones Newswires; +31 20 571 5201; maarten.vantartwijk@dowjones.com