Nortel Networks (NT) filed for bankruptcy protection in Delaware on Wednesday morning, according to reports.

Dow Jones Newswires reported that the telecom-equipment company had filed for Chapter 11 bankruptcy protection in Delaware. It also reported that the Canadian parent company filed for Chapter 15 bankruptcy protection in Delaware.

Shares of Nortel had fallen more than 20% on Tuesday. The company was due to make an interest payment of around $107 million on Thursday, and the markets had concerns whether the company would be able to make the payment.

Dow Jones Newswires reported that court filings show the company owes bondholders more than $3.8 billion.

Nortel has come under pressure during the global downturn, as companies spend less on its products and as it has faced competition from rivals such as Alcatel-Lucent (ALU).

Nortel was reportedly expected to file for bankruptcy protection in Canada, too.