NASA advanced its target of returning humans to the Moon by four years, but a request for $1.6 billion funding in addition to the proposed $21 billion for the agency over the 2020 fiscal year has been rejected, the media reported.

The White House made the request for additional funding on May 14.

But according to a report on Quartz on Wednesday, the House Committee on Appropriations, which controls the government's purse, left that additional request out of NASA's spending plan.

NASA announced plans to return astronauts to the Moon within five years after Vice President Mike Pence said in March that the nation's 2028 lunar touchdown plan was "just not good enough".

However, the US space agency will need a lot more cash to achieve its new target.

The White House had proposed that the additional funding comes from unused cash from an aid programme, the Pell Grants Programme, designed to help low-income students get to college, but the chair of the committee, Nita Lowey called it an "unconscionable proposal," according to Quartz.

The Committee on Wednesday revealed the funding bill was approved and NASA would be funded to the tune of $22.32 billion, but that additional cash will not be funnelled into lunar lander development and instead go into other NASA programmes unrelated to the Moon mission, CNET reported.