A Belgian judge agreed on Wednesday to release Greek MEP Eva Kaili, charged with corruption under the Qatargate graft inquiry, from custody and into house arrest pending her prosecution.

"She is under house arrest in Belgium and placed under electronic surveillance. The investigating judge has just made the decision," Antoon Schotsaert, a magistrate at the Belgian federal prosecutor's office, told AFP.

Kaili, who has become the public face of a scandal that rocked the European Parliament, was the last suspect still in pre-trial detention, four months after her arrest last year.

The 44-year-old ex-newsreader, formerly a vice-president of the parliament representing the centre-left bloc, has protested her innocence throughout the investigation.

Four more accused, including her partner and the father of her two-year-old daughter Francesco Giorgi, had previously been released from custody wearing electronic trackers.

According to the prosecutor's office, Kaili, who is from the northern Greek city of Thessaloniki, will be allowed to reside at her Belgian address while the probe continues.

She was initially arrested on December 9 last year when Belgian police raided a series of addresses tied to political figures in the Brussels region and seized more than 1.5 million euros in cash.

Investigators allege that a former MEP, Pier Antonio Panzeri, ran a network of MEPs, NGO leaders and trade unionists prepared to take bribes to advance the interest of Qatar and Morocco.

Both governments strenuously deny any wrongdoing, but Panzeri's lawyer has said that he is cooperating with the investigation in full in the hopes of negotiating a lighter sentence.

Panzeri's confessions led to the arrest in February of Belgian Socialist MEP Marc Tarabella. Tarabella was released to house arrest on Tuesday.