The group also said there were indications that other defendants could be released in the next few days, even as their trial proceeds.

The defendants, mostly female activists who had campaigned for the kingdom to expand freedoms for Saudi women, were arrested last spring and accused of acting as foreign agents and working to undermine the security of Saudi Arabia.

Branded as traitors, they were charged with making illegitimate contacts with foreign journalists and diplomats. But rights groups say the women are effectively on trial for their activism, and dozens of countries have called for their release. A panel of British members of Parliament and a group of nine United States senators have also asked Riyadh to let the women go.

Some of the women’s supporters said on Thursday that they hoped the temporary releases were a sign that international pressure had worked, pushing the Saudi authorities toward granting them full freedom, perhaps by sentencing them to time already served.

But they cautioned that the handling of the cases had been unpredictable from the start.

“While they’ve been released, their sham trial is still going,” said Rothna Begum, a Human Rights Watch researcher who has been tracking the cases. “We really don’t know what the authorities are going to do next. But we hope that the ordeal will be over soon.”