Ottmar Breidling, one of the lead counsels in the trial, told reporters that statements made by the four men could stretch to 1,000 pages.
The initial hearings ended this week and the statements will be studied ahead of their official reading to the court, scheduled for August 10, after the summer recess.
The suspects began making their confessions in late June, some two months after their trial began.
It is one of the biggest terrorism trials in Germany since the urban guerrillas of the Red Army Faction faced court in the 1970s.
Two of the suspects, Fritz G. and Daniel S., aged 29 and 23 respectively, are German converts to Islam. A third suspect, Attila S., is a 24-year-old German citizen of Turkish origin, while 30-year-old Adem Y. is a Turkish national.
Suspects accused of planning massive attacks
The so-called Sauerland cell is named after a region near Frankfurt where three of the men were apprehended in September 2007 along with 26 detonators and 12 drums of hydrogen peroxide, a substance used in the deadly attacks on London's transport system two years before. Attila S. was later caught in Turkey.
Authorities say the group aimed to carry out attacks as deadly as those of September 11, 2001 which killed more than 3,000 people in the United States.
The suspects face 15 years in prison if convicted on charges of belonging to a terrorist organization and conspiring to mount at least three bomb attacks in German cities targeting US citizens.
Prosecutors accuse the four of acting on behalf of the Islamic Jihad Union (IJU), a militant Islamic extremist group with roots in Uzbekistan and ties to al Qaeda. However, the Dusseldorf court has revealed that defendants continue to deny membership of the IJU.
Editor: Nathan Witkop