The embattled lender's longer-dated bonds suffered the sharpest declines. The 2032 issue lost more than 7 cents to dip below 70 cents in the euro before retracing some losses to trade at 71.8 cents, Tradeweb data showed. The 2033 bond dropped as low as 53.0 cents in the euro,
The bank, which is in the process of a radical overhaul, said last week it was pressing ahead with its strategic review due to be published later in the month which includes potential asset sales.
"The big question is what are the losses they have to take on asset sales and what does that do to your capital ratio and do we need to do a new rights issue?" said Joost Beaumont, senior fixed income strategist at ABN AMRO in Amsterdam.
"The answer is nobody really knows which is why we are seeing this sell-off," Beaumont said, adding Credit Suisse was among the top debt issuers in the sector.
According to the bank's second quarter financial report, Credit Suisse had outstanding long-term debt of 158 billion Swiss francs ($160 billion), including senior and subordinate instruments.
Credit default swaps (CDS) for Credit Suisse - instruments used to insure exposure to the lender's debt - stood at 250 basis points (bps) on Monday - a sharp increase from the 57 bps at the start of the year, data from S&P Global Market Intelligence showed.
Meanwhile, Credit Suisse shares slid by as much as 10% on Monday.
($1 = 0.9900 Swiss francs)
(Reporting by Karin Strohecker and Dhara Ranasinghe; Editing by Mark Potter)