The 193-member United Nations General Assembly has agreed a core budget of $5.4 billion for the next two years, marginally smaller than the amount allocated for 2014/2015, as top contributor the United States pushes for improved efficiency and cost management, Reuters reports.

The core UN budget, down from $5.5 billion in the previous two-year period, was agreed by the General Assembly late on Wednesday, December 23. It does not include peacekeeping - which has a separately negotiated budget of $8.27 billion for the year to June 30, 2016 - or the costs of several major UN agencies funded by voluntary contributions from member states.

"The budget you have approved reflects the difficult global financial reality we have faced for a number of years," UN Secretary-General Ban Ki-moon told the assembly. "Funding continues to shrink while demands on the United Nations grow."

The United States, which is the top contributor and pays the maximum 22 percent, said a number of funding cuts and improvements in efficiency had been made and the 2016/2017 budget was a "great step forward" for reforming management and budgetary practices.

"For the first time in 26 years, the committee adopted a staff compensation package that slows previously-mounting staff costs, which had hindered service delivery," said a U.S. official.

"The elimination of 150 redundant posts is a further step in the direction of the organization's efficiency, as are 5 percent reductions in supplies, travel, and furniture and other equipment costs," the official said.