(Adds Finland background, government comments)
STOCKHOLM/HELSINKI, March 15 (Reuters) - Nordea, the Nordic region's biggest bank, won shareholder approval on Thursday to transfer its headquarters from Sweden to Finland - the first time since the 2008 financial crisis that a major bank has moved to avoid tougher rules.
The bank is moving to cut the costs of complying with Swedish regulations and to fall under the supervision of the European Central Bank (ECB).
Nordea says it wants a level playing field with rivals supervised by the ECB, which since 2014 has sought to establish common standards across the euro zone, which includes Finland but not Sweden.
"We only have one fifth of our business in Sweden. We are actually more a European bank than a Swedish bank or a Finnish bank," Chairman Bjorn Wahlroos said at the bank's annual general meeting, which voted overwhelmingly on Thursday to approve the move.
"The (euro zone's) European Banking Union gives us a regulatory framework, and a stable framework, that is actually equal," he said.
The Swedish government has long sought higher taxes on the banking sector, much to Wahlroos's annoyance.
Nordea said a year ago it could move its headquarters if the Swedish government raised fees to cover the cost of winding up failed banks, prompting the centre-left coalition to soften some terms.
Sweden's demand for big capital buffers has acted as a stamp of quality for buyers of bank debt, lowering borrowing costs for Swedish banks.
Finland, which is only just recovering from a decade of economic stagnation, celebrated Nordea's move. The bank is set to become the largest company run out of Finland, overtaking Nokia in market value.
"This is a significant thing to our economy... The decision proves that Finland is an attractive environment for large companies," Finance Minister Petteri Orpo said in a statement.
"This government will not tighten corporate tax or bank fees, that would not be in no-one's interest."
The move's immediate economic benefits will be limited but Helsinki hopes the move would help its financial sector compete and encourage new players to the country.
Meanwhile, the vote makes Finland the smallest country in the world to host a bank classed by regulators as systemically important globally, and bring with it a balance sheet of more around 600 billion euros - close to triple Finland's annual economic output.
However, regulators considers the risk that Nordea would ever require state money as very small.
"Large banks will not anymore be only a risk for taxpayers as the main responsibility will be on private investors," Orpo said.
Finland's financial watchdog said it would hire around 30 new employees to help it oversee Nordea.
Nordea's move drew strong criticism in Sweden, with unions and politicians accusing the bank of being greedy and shortsighted.
The Swedish Shareholders' Association voted against the proposal, arguing that more time should have been taken over such an important decision and that conditions for banking in Sweden could change after a September general election.
"It's not like changing your shirt," said Per Westerberg, chairman of the association. "We don't vote 'no' because we think the arguments are wrong, but because the board is moving too fast," he said.
Nordea expects one-off savings of around 0.9 to 1.2 billion euros from the move, which it expects to happen by October.
Nordea's proposal to move, which needed a two-thirds majority to pass, got 96 percent of the votes at the meeting. (Reporting by Johan Ahlander and Jussi Rosendahl, Editing by Adrian Croft and Toby Chopra)