The request to reconvene on 23 April was made on Saturday during a closed-door court session, according to Salih al-Khathlan, who represented the Saudi National Human Rights Association (NHRA) at the hearing.
The trial of Ali al-Dimaini, Abd Allah al-Hamid and Matruk al-Falih, who have been held for more than a year, has been adjourned twice after a similar request by the prosecutor.
"We believe that such a delay is not necessary ... . All evidence should be available bearing in mind that the defendants were arrested more than a year ago," al-Khathlan said outside the court.
Al-Dimaini, al-Hamid and al-Falih were arrested on 16 March 2004 on charges of demanding a constitutional monarchy in the ultra-conservative kingdom.
The three, whose trial opened last August, are also accused of "using Western terminology" in demanding political reforms. Morever, they allegedly questioned the king's role as head of the judiciary.
They have repeatedly refused to respond to the charges until the trial is made open to the public, but al-Dimaini decided on Saturday to present more than 25 pages in his defence, a relative attending the hearing told AFP.
Al-Dimaini decided to speak because he felt that the proceedings had "hit a brick wall" after the judge's decision not to admit the public, the relative said.
The courthouse was guarded by
dozens of armed policemen
"I do not want my demands for comprehensive political reform to be reduced to a mere request for an open trial," Dimaini told the judicial panel, according to the relative.
Al-Khathlan said al-Dimaini addressed the panel for an hour and a half and that he argued his activities "were all within the framework of calling for reform" in the oil-rich kingdom.
Al-Falih and al-Hamid, meanwhile, maintained they would not respond to the charges, at least until the trial is opened "to representatives of the media", relatives said.
Dozens of armed policemen kept some 15 supporters more than 100 metres away from the courthouse entrance.
"We believe that
such a delay is not necessary ... . All evidence should be available bearing in
mind that the defendants were arrested more
than a year ago"
Saudi National Human Rights Association
The defendants were among more than 10 activists arrested at the time. The others were released in the same month after pledging to stop lobbying for reform in public.
Abd al-Rahman al-Lahim, spokesman of the trio's defence team and who had repeatedly and publicly criticised judicial practices during the trial, was arrested in early November. He has yet to be charged.
Al-Falih's relative Muhana al-Falih, who has been active in calling for the defendants' release, was also arrested in November without charge.
The crackdown on constitutional reformists has cast doubt on the government's attempts to introduce limited reforms, claimed to fit Saudi specifications rather than following a Western pattern.