(Adds details on amount of reserves earmarked)
* Budget bill sees gov't using up to $5.674 billion
* Growth estimated at slower 5.1 pct vs 8.3 pct 2011
* Primary budget surplus seen rising to 2.22 pct/GDP
BUENOS AIRES, Sept 19 (Reuters) - Argentina's government plans to continue tapping billions of dollars from the central bank's foreign currency reserves to pay debt for a third year in 2012, the budget bill showed on Monday.
The center-left government, which submitted its budget plan to Congress last week, expects continued use of reserves even as "excess" reserves shrink and concerns over the global economic outlook intensify. For details, see
Next year's budget bill, a copy of which was obtained by Reuters, said the government would tap up to $5.674 billion from the central bank in order to meet debt repayments to private creditors.
"As a way to guarantee the state's ability to meet its debt obligations even in adverse circumstances ... continued use of the (reserves) is forecast," the bill said.
It defended the reserves fund as a way to avoid the use of alternative financing sources "that imply a degree of reduction in the freedom of the nation's economic policy."
Last year's budget bill, which was never passed by Congress, stipulated the use of up to $7.5 billion.
The bill is expected to pass this year due to a politically weak opposition after President Cristina Fernandez's landslide primary election win in August put her on track for re-election on Oct. 23.
Argentina's former central bank chief was forced out of office in 2010 for resisting the government's drive to use reserves, but the funds were quickly replenished thanks to booming exports and a stable exchange rate.
That is not as true now with capital flight rising and the trade surplus shrinking. So while the unorthodox move is less controversial politically, it is seen as riskier economically.
The so-called excess reserves -- which surpass the amount needed to back the country's monetary base -- fell to $5.9 billion from $11.2 billion in January, the latest central bank data shows.
At the same time, concern is growing over the impact of global jitters on Latin America's No. 3 economy and the budget bill sees expansion slowing to 5.1 percent in 2012 from an estimated 8.3 percent in 2011.
The bill estimates inflation next year of 9.4 percent, down slightly from 9.7 percent for 2011, the bill showed.
Argentina's trade surplus, which has narrowed this year, is estimated at $8.58 billion in 2012. The bill sees the 2011 surplus at $9.04 billion.
With regards to the primary budget surplus, the government expects the surplus to increase to 2.22 percent of GDP, up from an estimated 1.38 percent this year.
The peso currency , which has depreciated more rapidly so far this year, is estimated 4.4 pesos per U.S. dollar compared with 2011's 4.13 pesos per dollar.
The document did not say if the estimate referred to an average or to the year-end estimate. ($1 = 4.205 Argentine pesos) (Reporting by Alejandro Lifschitz, Helen Popper and Jorge Otaola; Editing by Diane Craft and Ramya Venugopal) (email@example.com; +54-11-4510-2505; Reuters Messaging: firstname.lastname@example.org))