* Coalition government reshuffles key ministries
* Current justice minister becomes finance minister
* In charge during UBS bailout, struck deal with U.S.
ZURICH, Sept 27 (Reuters) - The Swiss government has made one of the main brokers of the UBS tax deal with the United States, Eveline Widmer-Schlumpf, the new finance minister in a surprise reshuffle of key ministries.
Widmer-Schlumpf will move from the justice ministry to take over finance from Hans-Rudolf Merz, who announced his retirement in August, the government said in a statement on Monday.
Her justice department played a key role in negotiating the deal that got the country's largest bank UBS off the hook in the United States, where a damaging tax case threatened its future.
The highly popular Widmer-Schlumpf, 54, also led the finance ministry on an interim basis during the bailout of UBS in October 2008 after Merz suffered a heart-attack.
The reshuffle follows the election of two new members to the seven-minister Federal Council, or cabinet. Merz from the Free Democrats (FDP) and Infrastructure Minister Moritz Leuenberger from the Social Democrats (SP) resigned this summer to allow a partial renewal of the council before the 2011 parliamentary elections.
Under the Swiss system, the major parties hold seats on the government according to a "magic formula", loosely based on the number of seats they hold in parliament.
The ministers take decisions by consensus and usually do not disclose dissenting views.
The federal government's powers are limited by Switzerland's strong federalism and citizens can challenge laws and decisions via referenda.
FRONTRUNNER
Newly elected FDP Federal Council member Johann Schneider-Ammann will take over the economy ministry from incumbent Doris Leuthard.
Leuthard will replace retiring Leuenberger at the infrastructure ministry, which is seen as one of the more senior posts because it carries more clout in country-wide issues.
The other newly elected councillor, Social Democrat and consumer advocate Simonetta Sommaruga, will take over the justice department.
The finance ministry will lead the lawmaking process towards tougher bank regulation and is also in charge of negotiating new double taxation agreements with countries such as Germany. These are crucial for Swiss banks, which have come under pressure during the global hunt for tax evaders.
Widmer-Schlumpf became a minister in 2007 as member of the right-wing SVP, but later founded a new party, the moderate-conservative BDP.
During her tenure as finance director of the eastern canton (state) of Graubuenden, Widmer-Schlumpf was also on the Swiss National Bank's supervisory board.
(Reporting by Sven Egenter; Editing by Ruth Pitchford)