LONDON - Governments around the world will borrow roughly $7.4 trillion this year, credit rating firm S&P Global estimated on Thursday, pushing their overall debt total to a record level for the third year in a row.

The annual forecast by S&P projected that the United States will make up one third of the total and together with Japan would account for over half of the $7.4 trillion.

China is number three and expected to issue around $700 billion worth of debt, while Italy, France, and Brazil will each raise over $180 billion.

"The Group of Seven nations account for some 70 percent of global borrowing and debt," the report said.

"Although four eurozone sovereigns - Italy, France, Germany, and Spain - are among the top 10 borrowers, we expect that euro zone member sovereigns together will issue only 40 percent of what the U.S. is likely to issue this year."

In a breakdown by region, Asia-Pacific sovereigns are expected to borrow $2.9 trillion, some 40 percent of the total, mostly by Japan and, to a lesser extent, China and India.

That is followed by North America at 34 percent and Europe at 18 percent including Russia and other Commonwealth of Independent States. Latin America meanwhile will account for less than 5 percent and Africa and the Middle East just over 3 percent.

In terms of the overall global sovereign debt level, even though borrowing as a share of GDP has been decreasing gradually since 2014 due to low interest rates and easier refinancing conditions, the headline amount is expected to keep climbing.

"We project that the global sovereign commercial debt stock will rise during 2018 by over $1.1 trillion to reach an all-time high of $47.3 trillion by the end of this year -- up by 2.5 percent, at projected market exchange rates," S&P said.

(Editing by Matthew Mpoke Bigg) ((marc.jones@thomsonreuters.com; +44)(0)(207 542 9033; Reuters Messaging: marc.jones.thomsonreuters.com@reuters.net Twitter @marcjonesrtrs))