The presiding judge granted the prosecutor's request on Saturday to bring more evidence against reformists Ali al-Dumaini, Abd Allah al-Hamid and Matruk al-Falih, who have been held for a year, representatives of the defendants said.
The previous hearing, also held behind closed doors on 16 February, was adjourned after the trio refused to cooperate unless family members and the media were allowed to attend.
Activists stay silent
Representatives said the three activists also refused to respond to the charges on Saturday because the trial was not open to the public.
The prosecution's request for a three-week period to bring evidence is the second in a row, "which is causing a prolongation of the arrest," lawyer Khalid al-Mutairi said after the hearing.
Representatives of the defendants charged that the prosecution was deliberately prolonging the trial.
"They are academics who are concerned about their country, not radicals who want to oust the regime"
Wife of defendant
The prosecutor presented during the hearing two televised interviews with Hamid and Falih, as part of evidence on previously announced charges, representatives said.
At the request of one of the judges, the televised images were covered in order to avoid seeing the female presenter, representatives said.
Dumaini, Hamid and Falih were arrested almost a year ago on 16 March 2004 on charges of demanding a constitutional monarchy in the conservative oil-rich Muslim kingdom.
The three, whose trial opened last August, are also accused of "using Western terminology" in demanding political reforms.
They also allegedly questioned the king's role as head of the judiciary.
The defendants were among about a dozen activists arrested at the time. The others were released in the same month after pledging to no longer publicly lobby for reform.
Dozens of policemen armed with machine guns kept a small number of supporters some 100m away from the entrance to the courthouse.
Falih's wife, who was not allowed into the courtroom, said she remains hopeful a solution will be reached soon.
"I hope the government will take their positions in consideration. They are academics who are concerned about their country, not radicals who want to oust the regime," she said.
Mutairi said he demanded again the release of the defendants on bail of their addresses, which means they would not move address before the end of the trial. Such a request was put through by the defence team at the first hearing on 9 August.
The Saudis have deployed tight
security around the court
Only two members of the seven-strong defence team continue to attend hearings as four were dismissed by the judge and another was arrested.
Abd al-Rahman al-Lahim, the spokesman of the trio's defence team, who had repeatedly and publicly criticised judicial practices during the trial, was arrested early in November. He is yet to be charged.
The crackdown on constitutional reformists has cast doubt on the government's attempts to introduce limited reforms, claimed to fit Saudi Arabian specifications rather than following a Western pattern.
Landmark three-stage municipal elections, which kicked off on 10 February, were generally praised as a major step towards reform, but calls for reform continue to receive criticism from government partisans.
"Some who are devoted to their nation, have headed towards reform but there remain some who run after fame. These are the ones engaging in reckless adventures," the imam of the holy mosque in Makka, Shaikh Abd al-Rahman al-Sudais, said in his Friday sermon in an apparent reference to the trio standing trial.