UNITED NATIONS - THE United States owes US$1.2 billion (S$1.5 billion) to the United Nations, more than a quarter of the payments owed the world body by all member states, a senior UN official said on Thursday.

UN Undersecretary-General for Management Angela Kane told reporters that only 13 of the United Nations' 192 member states had paid in full as of Wednesday. The total arrears amounted to some $4.1 billion, up from $2.2 billion at the end of 2009, Ms Kane said.

The administration of President Barack Obama repaid all the money the United States owed the United Nations last year. US Ambassador Susan Rice told reporters on Thursday that Washington pays its UN dues 'in full and on time.'

She said there was an issue of 'contested arrears' - debts that Washington does not agree it owes the United Nations.

As the United Nations' single biggest contributor, Washington is responsible for roughly one-quarter of the UN peacekeeping budget and slightly less than a quarter of the separate UN regular budget.

The United States has had a history of being reluctant to pay its you.N. dues, with critics of the world body charging it has a bloated and sometimes corrupt bureaucracy. UN supporters say the dues are cheap at the price.

US owes UN US$1.2b arrears