Emilie Teresa Stigliani

Burlington (Vt.) Free Press

Update: For the latest news on this story, check the Burlington Free Press' follow-up on the Sanders FEC filing here.

Bernie Sanders received a warning from the Federal Election Commission, citing problems with his campaign's February finance report.

The letter states the report lists amounts of contributions, receipts, expenses and disbursements that "appear to be incorrect."

The letter also cites possible impermissible contributions that exceed the allowed limit per election cycle ($2,700 for individuals) along with donations that come from outside the United States and from unregistered political committees.

The FEC sent the letter Thursday to the campaign asking for more information regarding the report filed Feb. 20. The letter warned: "Failure to adequately respond by the response date noted above could result in an audit or enforcement action."

The Sanders campaign has until March 31 to answer the FEC's request.

Sanders campaign spokesman Michael Briggs wrote in an email that such inquiries are "standard" and the campaign would address the FEC's questions. He noted that 85,391-page report covering the month of January listed over 125,000 separate contributions.

"Inevitably there are questions that the FEC staff will have," Briggs wrote Friday afternoon in an email.

Hillary Clinton, Sanders' opponent for the Democratic presidential nomination, submitted a 18,642-page report for the same filing period. The FEC had not questioned the Clinton campaign's report as of Friday afternoon.

Briggs said the contributions in question involved about 200 donors who appeared to have gone over the contribution limit.

"This happens all the time in campaigns, and the FEC’s rules explicitly allow 60-days from receipt of an over-the-limit contribution for campaigns to remedy the excessive portion of the contribution," Briggs wrote.