UPDATE: Lawrence O’Donnell says he was wrong to report Trump’s alleged ties to Russian oligarchs, saying it was “an error in judgment” that hadn’t gone through the network’s verification and standards process.

Earlier:

MSNBC host Lawrence O’Donnell reported a new tidbit Tuesday night raising questions about President Donald Trump’s relationship with Russia.

“A source close to Deutsche Bank says Trump’s tax returns show he pays very little income tax and, more importantly, that his loans have Russian co-signers. If true, that explains every kind word Trump has ever said about Russia and Putin,” O’Donnell wrote on Twitter.

Mediaite reports O’Donnell elaborated on MSNBC Tuesday, saying “the single source” said the co-signers are Russian oligarchs with ties to President Vladimir Putin.

O’Donnell stressed the “if true” part of the source’s allegations, and did not say if he was able to corroborate the claims.

Trump has repeatedly refused to release his tax returns, but Deutsche Bank revealed in court papers Tuesday that Germany’s largest bank does have copies of tax returns in response to a subpoena requesting financial documents related to Trump and his family. Lawmakers have said they are seeking the banking records as they investigate possible “foreign influence in the U.S. political process" in the 2016 presidential election.

The Associated Press reports the bank blacked out the name of the person or people whose tax records it had, citing privacy rules. It said it also has tax records “related to parties not named in the subpoenas but who may constitute ‘immediate family’” of individuals named in the document request.

Deutsche Bank has lent Trump’s real estate company millions of dollars over the years. In 2014, he allegedly inflated his net worth by $4 billion in documents to the bank in a failed bid to buy the Buffalo Bills for $1 billion cash.

Trump and three of his children sued to stop the House Financial Services and Intelligence committees from getting the records on the grounds that the requests were overly broad and unconstitutional.

The 2nd U.S. Circuit Court of Appeals indicated last week it would take a hard look at the legality of the subpoenas. U.S. District Judge Edgardo Ramos said in Trump and his companies are “highly unlikely” to succeed in challenging them.

The Associated Press contributed to this report.