Mitt Romney’s campaign said Thursday it was working to correct the Republican candidate’s financial disclosures following reports that nearly two dozen funds, including a now-closed Swiss bank account, were not included on the forms as required.

The Romney campaign described the problems as “trivial” and said it was preparing “minor technical amendments” to correct any discrepancies.

But Democrats immediately pounced on the missing information as evidence that Romney should disclose more tax returns beyond records from 2010 and 2011 that he released earlier this week.

Rep. Debbie Wasserman Schultz (D-Fla.), chairwoman of the Democratic National Committee, said Romney should “come clean” by releasing tax returns from other years. She cited the example set by his late father, George Romney, who released a dozen years of returns during his 1968 campaign for president.

“He claimed that everything there was to know about his assets was already known,” Wasserman Schultz said. “Clearly, that was not the case.”

The Los Angeles Times reported Thursday that at least 23 funds or partnerships listed in Romney’s 2010 tax returns did not appear in financial disclosure forms that are required from each presidential candidate. Eleven of the accounts were based in tax havens such as Bermuda, the Cayman Islands and Luxembourg, and another was a Swiss account that Romney advisers have said was closed in 2010.

The revelations heighten the political challenge posed by Romney’s vast wealth, which is taxed at a low rate unavailable to most taxpayers because it comes from investments rather than regular wages. Romney and his wife reported paying an effective tax rate of 13.9 percent in 2010 on income of $21.6 million, which is less than half the income tax rate for the same amount of regular income.

The campaign has also struggled to grapple with questions about the purpose and scope of Romney’s significant overseas investments, many of which are held in countries known as popular tax havens.

Romney spokeswoman Andrea Saul dismissed Democratic criticism of the disclosure errors and said the eventual amendments to Romney’s filings “will not alter the overall picture” of his finances.

“The inescapable fact is that by releasing over 600 pages of information regarding his finances, Mitt Romney is clearly coming down on the side of disclosure,” Saul said. “Any document with this level of complexity and detail is bound to have a few trivial inadvertent issues.”

Federal election laws require presidential candidates to disclose their financial holdings to the Office of Government Ethics. Romney’s report was supposed to list all income and investments from Jan. 1, 2010, through the date it was filed, Aug. 12 of last year.