TOKYO, Dec 10 (Reuters) - Japan’s new government bond issuance for the current fiscal year is expected to top 110 trillion yen ($1 trillion) due to slumping tax revenues and the cost of funding a third stimulus package, three government sources told Reuters on Thursday. The amount would be an increase from roughly 90 trillion yen in new bonds the government had planned to sell in the year ending in March, partly to fund two previous spending packages. When including refinancing bonds to roll over past debt, total issuance of Japanese government bonds will exceed a record 270 trillion yen in the current year, the sources said. But the government will try to minimise any increase in bonds sold to financial institutions via regular auctions by tapping funds reserved from past bond issuance, they said.