The Greek MEP at the centre of a graft scandal linked to alleged bribes from Qatar rocking the European Parliament insisted she was innocent on Thursday and asked to be released from pre-trial detention.

Eva Kaili, 44, is "cooperating in an active manner" with the Belgian investigation and requesting release under electronic surveillance, her lawyer, Andre Risopoulos, said outside the Brussels courtroom.

The Belgian judge, who was only deciding custody terms and not weighing the case itself, was expected to give a decision later in the day.

Kaili, a former newsreader booted from her post as parliamentary vice president after police raids earlier this month, has become the public face of the alleged corruption case. Qatar officials have insisted that the Gulf monarchy played no role in any wrongdoing.

Another of Kaili's lawyers, Michalis Dimitrakopoulos, on Wednesday told reporters she feels miserable, "very troubled" and betrayed by her boyfriend and co-accused Francesco Giorgi.

"Things are difficult, but we have very strong legal arguments to set her free," he said, arguing that Kaili is "not a flight risk and not in a position to destroy evidence."

She was arrested on December 9 as Belgian police, searching a number of addresses, found €1.5 million in cash. Kaili was charged shortly afterwards and has been in detention since.

Another three suspects - her partner Giorgi; the head of an NGO allegedly used to funnel money; and a former MEP-turned-lobbyist, all of them Italian - were also arrested.

All four are charged with "criminal organisation, corruption and money laundering".

Closed door hearing

A Belgian judge authorised Kaili's arrest and detention on grounds she was allegedly caught red-handed with cash, meaning her usual parliamentary immunity could not be invoked.

Separate investigations have begun in Italy and Greece, and on Thursday Greek judicial sources said they had seized a 7,000 square metre plot of land bought by Kaili and Giorgi on Paris, in the Cyclades islands, and frozen a bank account held by the couple.

The MEP denies receiving money from Qatar in exchange for influencing decisions affecting it in the EU parliament.

Qatar also denies the bribery allegations and has warned that continued linkage of it to the scandal could "negatively" impact ties and its natural gas supplies to the European Union.

Thursday's hearing took place behind closed doors.

Greece has opened its own preliminary inquiry into corruption and money laundering.

Kaili's hearing was conducted separately from the three other suspects, who appeared before a Belgian court on December 14.

On that date, the court ordered Kaili's partner Giorgi and the former MEP, Pier Antonio Panzeri, to remain in jail.

The NGO head, Niccolo Figa-Talamanca, was ordered to wear an electronic bracelet to track his movements, but that was suspended on appeal.

Euros in a suitcase

Kaili's Greek lawyer Dimitrakopoulos said the day before the December 14 hearing that she did not know of the existence of the cash - €150,000, according to a Belgian law enforcement source - found in her home.

Risopoulos told Belgian newspaper Le Soir that she strongly denied that she had "partially confessed".

He contradicted reports saying she had admitted to asking her father to remove the money uncovered at her address.

Kaili's father was held in custody for two days after the police searches before he was released.

Panzeri's wife and daughter were arrested in Italy under a European warrant and could face extradition to Belgium in January to answer charges.

Apart from the money found in Kaili's Belgian apartment, police discovered €750,000 in a suitcase with the father, and another €600,000 at Panzeri's place.

An international union leader, Luca Visentini, said Tuesday he had received €50,000 from Panzeri's Fight Impunity NGO.

He said the cash was to cover expenditure for his campaign to take over as general secretary of the International Trade Union Confederation.

Visentini, who was detained for questioning during the Belgian police raids but later released while remaining a suspect, was suspended by the union's board on Wednesday pending internal investigations.