Fitch Ratings on Tuesday downgraded China’s sovereign credit rating for the first time in over a decade, highlighting concerns of a credit build-up in the world’s second-largest economy.

Fitch lowered China’s long-term local currency rating from from AA- to A+, the first major international agency to cut China’s sovereign credit rating since 1999.

The agency cited “underlying structural weaknesses” in the Chinese economy, such as low average incomes, lagging standards of governance and a rapid expansion of credit, reports the Financial Times. Shadow banking, or lending by non-bank lenders, is also a growing risk, according to Fitch.

The downgrade only applies to China’s yuan-dominated debt, which is primarily traded domestically, and not the foreign currency debt, FT reports.

China has faced concerns over its debt levels since 2009, when state-owned banks unleashed a surge of loans to boost growth during the global financial crisis.

Total credit in China, including various forms of shadow-banking lending, may have reached 198% of gross domestic product at the end of 2012, up from 125% in 2008, Fitch estimated.

“Ultimately we think China’s debt problem is going to require sovereign resources to resolve and debt will migrate onto China’s sovereign balance sheet. We don’t know what form this will take – central bailouts of local governments or of banks, perhaps,” said Andrew Colquhoun, head of Asia sovereign ratings at Fitch.