Argentine debt insurance costs tumbled across the curve on Thursday after a U.S. court gave the country more time to fight a debt ruling, allaying investors' fears of a technical default next month.

According to Markit data, Argentina's six-month credit default swaps fell to 20 percent in upfront terms from 41 percent at Wednesday's close. That implies a cost of $2 million to insure $10 million of Argentine sovereign debt for six months, down from $4.1 million.

One-year CDS tumbled to 30 percent from 48 percent and five-year to 46 percent from 55 percent.

Argentine sovereign CDS had soared in recent weeks after U.S. federal judge ordered the country to treat so-called "holdout" investors on par with holders of restructured debt. This could have led to default in December on $24 billion in debt.

But an appeals court granted it more time on Wednesday [ID:nnL1E8MSDD]

Argentina's portion of the EMBI Global bond index <11EML tightened 233 basis points.

"It's very positive because (the U.S. court) has pushed out the stay order until March and that means the government gets more time to see what it can do," said Kevin Daly, a portfolio manager at Aberdeen Asset Management in London.

(Reporting by Sujata Rao and Carolyn Cohn)