* Cbank keeps base rate unchanged for 6th month running
* Cbank, IMF warn over fiscal sustainability risks
* IMF says Hungary govt plans "bold but risky"
By Krisztina Than and Gergely Szakacs
BUDAPEST, Oct 25 (Reuters) - Hungary's central bank and the International Monetary Fund (IMF) on Monday criticised unorthodox government measures to fix the budget and boost growth, warning of risks to fiscal sustainability.
The National Bank (NBH) kept interest rates at a record low of 5.25 percent for the sixth month in a row as expected earlier on Monday, but warned of risks to inflation and markets from the deficit-cutting plans.
The IMF said the government's plans were "bold but risky", warning against changes Budapest envisages to the pension system, saying the reforms could undermine investor confidence and did not address the budget's structural position.
The government's plans include cuts in personal income tax, special taxes on the energy, telecoms and retail sectors as well as measures which pension industry figures have warned would add up to renationalisation of a successfully reformed system.
"The government's commitment to the 3 percent budget deficit target for 2011 was beneficial but ... caused a rift in ... making uncertain the effects of the measures on long-term sustainability," Governor Andras Simor said.
The NBH has kept rates at a historic low of 5.25 percent for most of this year after 10 months of easing aimed at reviving an economy that needed IMF and EU aid to pull through the global financial crisis.
The bank said in its statement on Monday that it may need to hike interest rates "if upside risks to inflation materialise or there is a sustained increase in perceptions of the risks associated with the economy".
Most analysts expect Hungarian rates to stay steady into next year as weak domestic demand keeps a lid on inflation, but the budget uncertainty makes it less clear how markets will treat both the forint and government bonds.
That said, the currency remains around one percent higher than at the central bank last meeting in September, trading around 274 against the euro on Monday amid supportive global sentiment.
IMF WARNING
The IMF's delegation head, Christoph Rosenberg, told a news conference on Monday after Article IV consultations with Hungary that the IMF had not discussed any new -- precautionary or other -- financing deal.
"We did not discuss this issue at all," Rosenberg said when asked whether Hungary signalled interest in the Fund's new precautionary credit line.
The government had ruled out a new deal with the Fund after it unexpectedly halted talks with lenders in July, but some market players were expecting it to backtrack on this stance.
Rosenberg said crisis taxes would help the government to meet its 3.8 percent of GDP budget deficit target this year, but measures announced so far were not quite sufficient to ensure that the 2011 target would also be achieved.
He also said the government's measures would help labour participation.
But he added the measures were also risky as it was uncertain how the economy would react to them and "(they) ...do raise questions about medium-term fiscal sustainability."
The IMF said Hungary's economy was expected to grow by close to 1 percent this year and by around 2.5 percent next year, but the reaction of the economy to the tax measures was uncertain.
The government has suspended payment transfers to mandatory private pension funds from November which will leave an additional at least 420 billion forints ($2.15 billion) in the state budget in the next 14 months.
"We cautioned the authorities against this step because we think that it may in the short term resolve a goal -- showing better fiscal deficits on a headline basis -- but does not address the structural fiscal position," Rosenberg said.
(Reporting by Sandor Peto; editing by Patrick Graham, John Stonestreet)