By Alex Brittain

LONDON--Large depositors at Cypriot banks could lose as much as 40% of their funds as part of bailout for the crisis-hit euro-zone nation, its Finance Minister Michael Sarris said Tuesday.

He said capital controls aimed at preventing deposit flight should only be in place for a matter of weeks.

Regarding the loss likely to be suffered by people with deposits of more than 100,000 euros ($128,530) in Cyprus' two biggest banks, he said: "The exact percentage is not yet decided but it is going to be signicant I am afraid."

"What I have seen suggests a number in that neighborhood" of 40%, he said.

Deposits of under 100,000 euros are guaranteed from loss, but depositors with more than that sum will have be forced to contribute to recapitalizing the banking system, via a system that will also see their money converted into bank shares, he said.

Mr. Sarris, who was being interviewed on BBC Radio, said he thinks banks will reopen on Thursday, after being closed for more than a week while the government negotiated terms of a bailout with the European Union, European Central Bank and International Monetary Fund.

He said capital controls aimed at preventing large-scale withdrawals of deposits won't last for months or even years, as has been the case in Iceland, another country that suffered a banking crisis.

"I think we are talking a matter of weeks," Mr. Sarris said.

The controls "will probably have a two-tier system", he said, with tighter restrictions on transactions at the two biggest banks, the Bank of Cyprus and Cyprus Popular bank, commonly known as Laiki Bank. The latter bank is due to be wound down.

He said the circumstances of the bailout will mean a "step backwards" for the Cypriot economy.

Write to Alex Brittain at alex.brittain@dowjones.com