The leader of Tunisia's Islamist movement was questioned in a Tunis court by the anti-terror unit on Tuesday before being released ahead of a national referendum on a new constitution.
Rached Ghannouchi, the leader of the Islamist Ennahda party and the speaker of the dissolved parliament, dismissed the summons as a political ploy.
He appeared surrounded by hundreds of supporters amid a heavy police presence.
After a "more than nine-hour" session and "19 defence speeches" requested by lawyers, Mr Ghannouchi left the anti-terror centre and returned home, his lawyer and former Ennahdha official Samir Dilou said on Facebook.
Mr Dilou told AFP the anti-terror unit had allowed Mr Ghannouchi freedom of movement, while another lawyer said the politician was not the subject of "judicial control measures".
The summons came less than a week before President Kais Saied holds a referendum on a new constitution that would greatly expand his powers, a move that Ennahda and several other parties have rejected.
The charges centre on corruption and money laundering over a small civil society organisation called Namaa, which investigators claim Mr Ghannouchi and Ennahda use to launder foreign funding.
Mr Ghannouchi, Ennahda and Namaa deny the charges.
"Namaa is an independent civil society organisation which has never had any financial dealings with Ennahdha party or any of its leaders," the party said in a statement.
As part of the same investigation, Tunisian authorities last month arrested former prime minister and one-time Ennahdha leader Hamadi Jebali for alleged money laundering.
Jebali was later released, but is due to face questioning on the allegations on Wednesday.
Earlier this month, a court ordered the freezing of the bank accounts of Mr Ghannouchi and a dozen members of his family and his party ― including Jebali ― as part of this investigation.
In June, Mr Ghannouchi was handed a ban from travelling abroad as part of a separate investigation into high-profile political assassinations that rocked the country in 2013.
Mr Ghannouchi, who was elected as speaker of parliament in 2019, has become one of Mr Saied's harshest critics. He has also criticised Mr Saied for his dismissal of parliament and takeover of the judiciary.
In a written statement released during the questioning, Mr Ghannouchi said: “I have come here today to appear before the Tunisian judiciary out of respect for it and in support of the existence of an independent judiciary — not a mere function as some wish it to become, who seek to belittle its role and status.” ― additional reporting by AFP