Olaf Scholz joins a long list of politicians and officials who have denied responsibility for slipshod oversight and what critical lawmakers see as a pro-Wirecard bias that failed to avert Germany's biggest post-war fraud.
The case, on a par with the Enron scandal in the United States, has prompted the resignation of the heads of two German supervisory authorities, an overhaul of regulation, and criminal investigations.
Jan Marsalek, Wirecard's former chief operating officer, has vanished since the technology company was busted for what accountants described as an "elaborate and sophisticated fraud".
Wirecard's former chief executive and founder Markus Braun turned himself in to police, but Marsalek is at large.
Germany's largest bank said last week that it was working with financial watchdog BaFin and Wirecard's insolvency administrator on possible support for Wirecard Bank.
"We all now need transparency and that's the first task to be done," Sewing said at a webcast event organised by Bloomberg News.
Emails sent to Senjo Group and Citadelle to the addresses listed on their websites could not be delivered. Wirecard said it was not making any statements at this time.
"The review surfaced reasons to suspect that offences may have been committed," the authorities said on Friday.
In a process managed by Credit Suisse, bonds convertible into Wirecard debt with a nominal value of 900 million euros ($1.01 billion) will be sold via an auction set to close on July 8, according to a document seen by Reuters.
The lawyer, Joerg Zarbl, told Reuters on Tuesday that Braun took out a 120 million euro ($135 million) loan to buy at least 2.5 million Wirecard shares.
German prosecutors are already investigating possible criminal offences in connection with the payments firm.
Several UK fintech firms have been forced to suspend services following the FCA's restrictions on Wirecard.
We cannot lift the restrictions without reassuring ourselves that the firm has been able to satisfy all our concerns for example that all clients' money is safe.
The United Kingdom’s Financial Conduct Authority (FCA) has ordered Wirecard Card Solutions Limited, a UK company to stop all its regulation financial activities, in addition to some other restrictions.