Mr Mueller, currently leading an investigation into whether the Trump campaign colluded with the Kremlin, reportedly requested documents and emails from over a dozen top campaign officials that include several keywords related to Russia.
A source told the Wall Street Journal the subpoena would not compel testimony before a grand jury. Mr Trump’s campaign was surprised by the order after voluntarily cooperating with previous requests from Mr Mueller’s team, the source said.
The subpoena reportedly marks the first time Mr Trump’s campaign has been ordered to turn over information.
Mr Trump’s campaign began handing over documents to Mr Mueller in September. One lawyer that represents Mr Trump has said the campaign was in “total cooperation” with the special counsel’s investigation.
Mr Mueller’s Russia probe has heated up in recent months. In October – five months after we was appointed to lead the inquiry – he announced 12 charges, including money laundering and conspiracy to defraud the US, against former campaign manager Paul Manafort and associate Rick Gates.
Both subsequently pleaded not guilty to all counts when they appeared in a federal court in Washington DC.
Mr Mueller subpoenaed Mr Manafort and several of his associates as well as several banks to obtain Mr Manafort’s financial records.
Earlier in October, former Trump campaign adviser George Papadopoulos had pleaded guilty to lying to FBI agents about his contacts with Russian officials.
Mr Trump has repeatedly insisted that there was “no collusion” and has called the Russia investigations – also being conducted by multiple congressional panels – a “witch hunt”.