* German tax deal faces stiff opposition from SPD
* President says German parliament could find consensus
* Staff increased to deal with foreign tax queries
BERNE, Oct 31 (Reuters) - The Swiss president is still hopeful that the German parliament will back a deal for Swiss banks to levy taxes on assets German citizens have stashed in secret accounts despite stiff Social Democrat (SPD) opposition.
Swiss Finance Minister Eveline Widmer-Schlumpf, who also holds the rotating position as president, said on Wednesday she still expected the deal to be passed by the end of the year in time to take effect on Jan. 1, 2013.
"There is a 50-50 chance that it is adopted," Widmer-Schlumpf told a public event held by Germany's Die Zeit newspaper in the Swiss capital, adding she had confidence in German Finance Minister Wolfgang Schaeuble to bring it through.
German Chancellor Angela Merkel's government agreed the deal with Switzerland earlier this year, but it still needs approval from Germany's upper house of parliament, which represents the states and where the government lacks a majority.
The SPD's nomination of Peer Steinbrueck - a critic of Swiss banking secrecy - to challenge Merkel in the German election next year - has stiffened his party's resolve to block the deal in a vote expected next month.
But Widmer-Schlumpf noted that even if the German upper house rejects the deal, it could still be salvaged in a mediation procedure that seeks to resolve differences between the upper and lower houses.
The agreement would require Swiss banks to levy a punitive charge on an estimated 150 billion euros ($195 billion) in undeclared money held by Germans in Swiss accounts and to tax future income, with the proceeds passed on to Germany without the identities of the account holders being revealed.
Britain and Austria have already ratified similar deals which will come into force next year and Switzerland hopes other countries - including Greece and Italy - will also follow suit.
FLOODED WITH PROBES
Earlier on Wednesday, the Swiss government said tax authorities will hire more staff to deal with a flood of requests for information from countries trying to track down tax cheats using Swiss bank accounts.
The government said it had granted permission for the finance department to add eight new staff to a group of six created in 2011,
It said the increase was necessary so that Switzerland could meet its international obligations in an efficient way, noting it had received 704 requests for assistance in tax affairs from foreign authorities so far this year, compared to 370 last year.
Since bowing to global pressure to weaken bank secrecy in 2009, Switzerland has agreed new double-taxation treaties with 25 countries, which can all now make more wide-ranging requests for information on the accounts of suspected tax dodgers.
Switzerland's $2 trillion offshore wealth management industry looks set to lose hundreds of billions of francs (dollars) as a result of steps to stop foreigners using secret accounts to evade tax.
It is also trying to end investigations by U.S. tax authorities into 11 banks, including Credit Suisse and Julius Baer, in return for the payment of hefty fines and the transfer of names of thousands of U.S. bank clients.