French President Emmanuel Macron takes part in a conference at the UCL university in Louvain-La-Neuve, on the last day of an official state visit in Belgium, November 20, 2018. REUTERS/Yves Herman/Pool

PARIS (Reuters) - French prosecutors on Tuesday opened an investigation into the source of funds worth 144,000 euros that helped finance President Emmanuel Macron’s election campaign in 2017, a source at the prosecutor’s office said.

The investigation comes after the National Commission for Campaign Accounts and Political Financing (CNCCFP) was unable to trace some donations made to Macron’s En Marche (On the Move) party by cheque and electronic transfer, the source added.

The unaccounted for funds represent a small fraction of Macron’s campaign spending. According to the CNCCFP, Macron raised 16.8 million euros in campaign finances -- below the cap set by French law -- and spent almost all of it.

Macron’s party did not respond immediately to a request for comment.

Paris prosecutors are also investigating alleged irregularities in the 2017 campaign spending of hard-left leader Jean-Luc Melenchon. The former Trotskyist was interrogated by police and his headquarters raided last month in connection with the allegations.

“Will they also raid Macron’s house? Will they confiscate his list of members and donors? Or will this be a case of double standards,” Melenchon tweeted.

The far-right party of Marine Le Pen, Rassemblement National (National Rally, formerly known as National Front) and the centrist Modem party are also investigation for alleged misuse of EU funds.