TOKYO (Reuters) - Japan is likely to miss its deficit-cutting target in fiscal 2018 because the government has delayed a sales tax hike by more than two years, public broadcaster NHK said on Friday, citing an unidentified source.

The Cabinet Office now forecasts the primary budget deficit will be 1.9 percent of gross domestic product in fiscal 2018 from 1.7 percent it projected in January, NHK said.

Prime Minister Shinzo Abe's government has a target of reducing the primary budget deficit to 1 percent of GDP in fiscal 2018.

The primary budget, which is an important measure of fiscal health, excludes debt servicing costs and income from bond sales.

In June, the premier decided to postpone the sales tax increase to October 2019 from of next April because of growing risks to the economy.

Japan's primary budget deficit is expected to be around 5.6 trillion yen ($52.90 billion) in fiscal 2020, improving from a 6.5 trillion yen deficit projected by the Cabinet Office previously, helped by an increase in tax revenue last fiscal year and the planned sale tax increase in October 2019, NHK said.

Japan's primary budget deficit has been narrowing and is seen likely to meet the target for fiscal 2015, which has not yet been finalised, halving the deficit as a percentage of GDP to the level last seen in fiscal 2010.

The government has stuck by its target of achieving a primary budget surplus by fiscal 2020 through boosting economic growth.

(Reporting by Kaori Kaneko; Editing by Eric Meijer)