SYDNEY, May 14 (Reuters) - Rating agency S&P said on Tuesday that Australia's budget for the fiscal year ending June 2024 could be mildly inflationary.

"While the Labor administration estimates that it has banked (rather than recycled into new outlays) approximately 88% of unexpected tax revenue upgrades since coming into office, today's budget slightly loosens the purse strings," the rating agency said in a statement after budget details were released.

Australia's government plans to spend billions to cut energy bills and rent, in measures it hopes will lower headline inflation and provide relief for voters grumbling about cost of living pressures ahead of an election next year.

S&P said it no longer expects the Reserve Bank of Australia to cut interest rates this calendar year. (Reporting by Alasdair Pal in Sydney; Editing by Kim Coghill)