* SVP to propose new rules in parliament next week
* Blocher already called for SNB head to quit
* Other parties accuse SVP of electioneering
ZURICH, March 6 (Reuters) - The popular right-wing Swiss People's Party (SVP) wants to limit the autonomy of the Swiss National Bank (SNB) on decisions outside its core mandate of price stability after big losses on currency interventions.
"If the SNB leaves its actual mission with large currency buys, one must be able to supervise the SNB bosses and if necessary stop them," Christoph Blocher, former justice minister and SVP mastermind, told the SonntagsZeitung newspaper.
Blocher has already called on SNB chief Philipp Hildebrand to resign after the central bank posted a 2010 loss of 19.2 billion Swiss francs ($20.74 billion) after ill-fated interventions to try to fight the currency's strength.
The SVP, expected to remain Switzerland's biggest party in national elections in October, plans a motion proposing new rules in parliament next week to control the central bank.
"In extreme cases, currency buys can be necessary to secure price stability. That is why we need disciplinary supervisory rules to prevent the managing board contravening their core mandate and taking on unbelievable risks," Blocher said.
The SNB has repeatedly defended the interventions as being necessary to fight deflation risk from the soaring franc.
Blocher also accused Hildebrand of being too much in favour of more integration with the European Union.
"I have the suspicion that Mr Hildebrand wants to play a role at the European or even global level. He pleads for opening and integration which does not belong to his area of competency. He also doesn't rule out tying the franc to the euro," he said.
However, the other main parties in the coalition government that rules Switzerland have defended the SNB's currency interventions and the central bank's independence.
Economy Minister Johann Schneider-Ammann said in an interview with the Finanz und Wirtschaft newspaper on Saturday that the SNB had managed to dampen the franc's rise somewhat and said the situation had improved in the meantime.
Otto Ineichen from the liberal Free Democrats told the Sonntag newspaper the SVP was going too far with its election campaign and was defaming the SNB with "false accusations".
The safe-haven franc has soared to record highs against the euro and the dollar due to unrest in north Africa and the euro zone's debt crisis, prompting calls for the government to intervene as Swiss exporters suffer.
The Swiss government has announced measures to help firms to deal with the strong Swiss franc, including increased funding for the tourism industry and support for companies to boost innovation. ($1=.9255 Swiss Franc) (Reporting by Emma Thomasson; Editing by Jon Loades-Carter)