UNITED NATIONS (Reuters) - The United States owes $1.2 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, Kane said. It has been a difficult year in many ways for many member states because of the economic recession, she said. The administration of President Barack Obama repaid all the money the United States owed the United Nations last year. United States Ambassador Susan Rice told reporters on Thursday that Washington pays its United Nations 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. They must be counting contested arrears if it gets to a figure which gets close to anything like that, she said in reference to the $1.2 billion figure cited by Kane. As the United Nations single biggest contributor, Washington is responsible for roughly one-quarter of the United Nations peacekeeping budget and slightly less than a quarter of the separate United Nations regular budget. The United States has had a history of being reluctant to pay its United Nations dues, with critics of the world body charging it has a bloated and sometimes corrupt bureaucracy. United Nations supporters say the dues are cheap at the price. Last December, the United Nations General Assembly approved a UN budget of $5.16 billion for 2010 and 2011. That did not include peacekeeping, currently running at some $8 billion a year and approved in separate negotiations, or the costs of several major United Nations agencies that have separate budgets.