Archbishop Wielgus, 67, resigned just minutes before being installed as the new archbishop of Warsaw on Sunday after admitting that he had collaborated with the country's secret police.
However, the Vatican had no knowledge of the allegations at the time of Archbishop Wielgus' 6 December appointment, Cardinal Re told Italian daily Corriere della Sera, according to a DPA report.
"When Monsignor Wielgus was nominated (archbishop of Warsaw) we knew nothing of his collaboration with the secret service," Cardinal Re said.
According to Corriere della Sera, Wielgus only decided to step down after being asked to do so by the pope in person. Benedict reportedly accepted his resignation on Saturday.
Earlier, the pope's spokesman, Fr Federico Lombardi, described his resignation as 'appropriate'.
Meanwhile, Polish TV station TVN 24 reports that the prelate of Wawel Cathedral in Cracow, Janusz Bielanski, offered his resignation Monday to Cardinal Stanislaw Dziwisz, who previously as secretary to Pope John Paul II, and it was accepted immediately.
Wprost news magazine had reported as early as one year ago that Bielanski was an informant for the former communist secret service, DPA says.
Accusations of collusion with the secret service against priests and spiritual leaders of higher rank have continued to fly around Poland.
Several clergymen in Dziwisz's circle of friends were systematically forced to cooperate with the secret service, Newsweek Polska reported Monday.
Wprost said that documents at the Institute of National Remembrance, which is responsible for overhauling the country's communist past, show that the bishop of Gniezno, Jerzy Dabrowski, who died in 1991, was an informant named Agent Ignacy by the secret service.
The bishop was one of the closest aides of Cardinal Stefan Wyszynski, who was head of the Catholic Church in Poland as primate until his death in 1981.
Meanwhile, Cardinal Jozef Glemp, the current Catholic primate of all Poland, came under increasing fire in the Polish media Monday for supporting Wielgus.
"The Primate's Big Mistake," was a headline on the front page of Dziennik daily. "The primate stood before the faithful to say clearly, 'If it had been up to me, Wielgus would be archbishop.'"
Glemp, who is now expected to lead the Warsaw archdiocese provisionally until a new archbishop is named, had continued to defend Wielgus during his Sunday sermon.
His actions placed him not only in opposition to the Vatican, but also against the majority of Catholics who found it intolerable that their spiritual leader had a secret service past, Dziennik said.
Polish journalist Aleksander Hall said that he now hoped for a "successor of great calibre and great credibility" to replace Wielgus at the head of the church in Warsaw.
"All possible mistakes were committed in this affair," Hall wrote in the Gazeta Wyborcza about the behaviour of Wielgus and the church hierarchy.
He appealed for a church investigation committee appointed by the bishops to uncover secret service involvement within the church.
Vatican accuses disgraced Polish prelate of misleading the pope (Monsters and Critics, 8/1/07)
Poland's Chief Roman Catholic Criticized (Times Daily, 8/1/07)
Another Polish Priest Resigns Over Secret Service Charges (Playfuls, 8/1/07)
Vatican denounces "strange alliance" against church after Wielgus resignation (AsiaNews, 8/1/07)
LINKS (not necessarily endorsed by Church Resources)
Profile: Stanislaw Wielgus (BBC News)
Archbishop Stanislaw Wielgus (Catholic-Hierarchy)
Archdiocese of Warsaw (Polish)
Archbishop Stanislaw Wielgus (Wikipedia, Polish)
New Warsaw Archbishop resigns over collaboration allegations (CathNews, 8/1/07)
Polish Cardinal says sorry over "super spy" slur (CathNews, 15/11/06)
Polish spies in John Paul II assassination attempt (CathNews, 13/10/06)
Cardinal claims Vatican priests spied on John Paul II (CathNews, 6/9/06)
9 Jan 2007