Senior Pakistani security officials told United Press International the codes were found in a building in Faisalabad. Last week, a joint FBI and local police team arrested one of bin Laden's key aides, Abu Zubaydah, and 18 other al Qaida suspects from the same building.
Abu Zubaydah is so far the most senior al Qaida leader to be arrested. U.S. officials told reporters in Washington earlier this week that they believe Abu Zubaydah was responsible for selecting and training volunteers for al Qaida.
"We found apparently incoherent sentences like, Friday: Dawood and Abu Kamel; Saturday: Osama and Anees, written on a wall inside a building in Faisalabad's Faisal Town area," one Pakistani security official told UPI.
The raiding party also found other names written beside other days, possibly indicating that people were required to do some kind of duty on a particular day.
Pakistani investigators had hoped that 28 al Qaida suspects arrested in last week's would help them understand the codes. "But they did not cooperate with us. They insisted that these words were written by the man who was killed when police raided their hideout and they did not know what they meant," said another Pakistani official.
Pakistani officials said investigators also asked the suspects if they had met or seen bin Laden anywhere in Pakistan after the fall of the Taliban regime in Afghanistan in November. "All of them said that they had not seen him since November. We did not necessary believe them," said one official.
Pakistani officials say most of the suspects are now in the custody of the U.S. officials, who are continuing the interrogation.
Meanwhile, the body of the alleged al Qaida member who was killed during the raid has been shifted from Faisalabad to an unknown place under tight security.
Officials at Faisalabad's Allied Hospital told reporters that some American officials, accompanied by Pakistani police, had collected blood and other fluids from his body for DNA tests.
He was later identified as Abul Hasnat, a 32-year-old Arab holding a Syrian passport.
The al Qaida terror network is suspected of masterminding Sept. 11 attacks on the World Trade Center in New York and the Pentagon, just outside of Washington, D.C.