Dagong Global Credit Rating Co, a Chinese rating agency, downgraded its US sovereign credit rating on Thursday despite Washington's resolution of the debt ceiling deadlock, warning that fundamentals for a potential default remained "unchanged."

Dagong lowered its ratings for US local and foreign currency credit from A to A-, maintaining a negative outlook, the agency said in a statement posted on its website.

The announcement came after the US Congress passed and President Barack Obama signed a bill that extends the nation's borrowing authority and ends a two-week government shutdown.

"The fundamental situation that the debt growth rate significantly outpaces that of fiscal income and gross domestic product remains unchanged," Dagong said, noting that Washington's solvency was vulnerable as old debts were still repaid through raising new debts.

"Hence the government is still approaching the verge of default crisis, a situation that cannot be substantially alleviated in the foreseeable future," the statement said.

Dagong made headlines in August 2011 when it lowered its main rating for US sovereign debt after the US Congress passed an earlier bill to raise Washington's debt ceiling.

The agency, which is less prominent than long-established Western competitors including Moody's, Fitch and Standard and Poor's, has been working to further raise its profile.

In June, the Milan-based branch of Dagong officially started conducting business in Europe after gaining authorization from the European Securities and Markets Authority, making it the first Asian rating company to operate in the European Union.

The Chinese agency is not alone in pointing out that the creditworthiness of the US is not as good as it once was. On Wednesday, Fitch put the Triple A rating it gives to the US under negative watch.

In August 2011, Standard & Poor's downgraded the US to AA+ after a protracted debt ceiling debate in Congress brought the government to the verge of a shutdown.