Global government debt reportedly hit $66 trillion through the end of 2018, and now accounts for about 80 percent of global GDP.

The worldwide IOU tab through 2018 is, as measured in U.S. currency terms, about double where it was in 2007, just as the financial crisis was beginning to unfold, CNBC reported, citing credit rating agency Fitch Ratings' new Global Government Debt Chart Book released Wednesday.

"Government debt levels are high, leaving many countries poorly positioned for financial tightening as global interest rates begin to move higher," James McCormack, Fitch's global head of sovereign ratings, said in a statement.

Debt in developed countries has remained fairly steady, around $50 trillion, since 2012, though that's not true of the U.S. Total public debt for the American government has jumped from $15.2 trillion to $21.9 trillion, or 44 percent, during the period, CNBC reported, citing Treasury Department data.

Fitch said the total U.S. debt is nearly 10 times the size of France, Germany, Italy and the U.K. combined.

Fitch said emerging market economy debt surged 50 percent in the period since 2012, from $10 trillion to $15 trillion.

Meanwhile, the credit quality of this debt has undergone a “steady deterioration,” Fitch said. Just 11 sovereigns hold the highest possible credit rating, AAA, while the proportion of outstanding government debt that is junk-rated is hovering around its highest level for 15 years, at 7 percent of the total, the Financial Times reported, citing Fitch data.

The average rating in developed markets is below AA, down a grade since 2011, while in emerging economies the average rating is at its lowest since 2005, sitting just below BB+. This leaves governments precariously poised as the global credit cycle tightens, according to Fitch.

Fitch isn't alone in its warning.

IMF Managing Director Christine Lagarde said on Monday that the risk of a sharper slowdown in global growth had increased, even if recession was not yet around the corner.

Speaking at the World Economic Forum in Davos, Switzerland after the IMF trimmed its 2019 and 2020 global growth forecasts, Lagarde urged policymakers to address economic vulnerabilities, especially by reducing high government debt, Reuters reported.

• IMF: Global Debt Threatens Markets as China, US Continue to Spend
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