Torres, 63, was taken into custody at her residence in an exclusive suburb of Guatemala City, prosecution spokeswoman Julia Barrera told reporters.

She said Torres was facing charges “for the crimes of unregistered electoral financing and illegal association.”

The centre-left Torres, whose ex-husband Alvaro Colom was president from 2008-2012, has been suspected of involvement in corruption but enjoyed immunity because of her status as a presidential candidate.

She lost an Aug 12 run-off to conservative Alejandro Giammattei.

Arriving at the court for her arraignment, she accused Giammattei of pressing for her arrest.

“It’s a political persecution,” she told reporters.

Prosecutors had appealed in February for Torres’s immunity to be withdrawn to allow them to investigate claims that US$2.5 million in donations to her 2015 election campaign went unreported.

The funds were donated to her National Unity of Hope party by two Guatemalan companies but were never registered with electoral authorities, prosecutors say.

The investigation was assisted by the UN International Commission Against Impunity (CICIG).

Its mandate ends on Tuesday after President Jimmy Morales disavowed an earlier promise to extend it for a further two years.