The Muslim Brotherhood, banned since 1954 but tolerated by the government, has become the country's biggest opposition group with support from a fifth of the legislators in parliament.
Al Jazeera's Amr el-Kahky, reporting from Cairo, said hundreds of supporters gathered outside the court at the Haekstep military base waving posters of the detained leaders.
He said there was widespread anger at the government for using the delay tactic for political gain.
Men, women and children chanted anti-government slogans and denounced the trial as unfair.
"Terrorism or money laundry, where is the evidence? State security, you thugs, you protect the thieves!" they shouted.
In 2006, Mubarak had ordered the 40 Brotherhood leaders to be charged with money-laundering and terrorism in a military court.
Thirty-three of them have been in custody since December 2006 while seven others are being tried in absentia.
An appeals court later ruled that they should be tried before a civilian tribunal but the state overturned the decision and trial resumed last year before the military court.
Abdul Monim Abdul Maqsoud, the group's lawyer, said Egyptian authorities were using the delay to prevent any wide scale Brotherhood action before the April 8 municipal elections.
"It's a political case. The postponement has to do with the local elections," he said. "Now that the verdict is delayed the government can buy time for political gain."
Muslim Brotherhood candidates won 20 per cent of the seats in the 2005 parliamentary elections, prompting Mubarak to delay the municipal elections originally set for April 2006.