(Reuters) - The U.S. government has nearly $36 trillion of debt on issue and its bonds are the bedrock of the global financial system.

President Donald Trump said Sunday his administration was examining Treasury debt payments for possible fraud and suggested that the country's debt might not be that high - remarks that may unsettle investors who regard the U.S. as creditworthy and its debt as a safe asset.

Treasuries are held widely and used globally as financial reserves, as a benchmark for pricing and as collateral for borrowing. Below is a breakdown of U.S. debt ownership.

By owner:

Owner Holding size (U.S.

dollars)

U.S. Federal Reserve $4.7 trillion

system

Social Security and $2.4 trillion

other U.S. agencies

Foreign investors $8.7 trillion

U.S. investors and $19.7 trillion

other U.S. holders

And by foreign investor:

Country/Region/City Holding size (U.S. dollars)

Japan $1,099 billion

China $768.6 billion

Britain $765.6 billion

Luxembourg $424.5 billion

Cayman Islands $397 billion

Canada $374.4 billion

Belgium $361.3 billion

Ireland $338.1 billion

France $332.5 billion

Switzerland $300.6 billion

Taiwan $286.9 billion

Singapore $257.7 billion

Hong Kong $255.7 billion

India $234 billion

Brazil $229 billion

Norway $159 billion

Saudi Arabia $135.6 billion

South Korea $127.8 billion

Mexico $100.8 billion

Germany $97.7 billion

Rest of World $1,589 billion

Foreign ownership data is compiled monthly by the U.S. Treasury, which says it relies mostly on U.S.-based custodians and that because securities held in custody accounts may not be attributed to the actual owners, the data may not provide a precise account of individual country ownership of Treasuries.

Total U.S. debt is $35.5 trillion and it has been rising.