A former US judge on Twitter accused of spying for Saudi Arabia has been released on bail by a US judge, while two Saudis are still at large in Saudi Arabia.

Judge Paula Mcandlis said her decision would take effect at 4:30 pm (local time) unless federal prosecutors appealed.

Defense attorney Chris Black said that if prosecutors appealed the judge's decision, Abu Amo would have to remain in custody until a judge in the District Court considered the decision.

Abu Amo appeared before the Federal Court in Seattle, Washington, US in a second session on Friday on charges of spying for Saudi Arabia.

Abu Amo, 41, and a Saudi national, Ali Al Zubara, 35, are accused of spying for Saudi Arabia and illegally obtaining personal information from Twitter users who criticize the kingdom.

Abu Amo appears to have spied on several accounts between the end of 2014 and the beginning of 2015 for a luxury watch and at least $ 300,000.

In 2015, Ali Al-Zubarah submitted data on at least 6,000 accounts, particularly about Saudi dissidents whose family had sought refuge in Canada, according to the indictment.

The US Justice Department on Thursday accused Abu Amo and the Zubara family of spying for Saudi Arabia and "being illegal agents of a foreign government."

"The criminal complaint disclosed today (Thursday) accuses Saudis of searching Twitter's internal systems to obtain personal information about Saudi dissidents and thousands of Twitter users," US Attorney General David Anderson said in a statement.

"US laws protect US companies from such illegal outside penetration, and we will not allow the use of US companies or technology," he said. The assistant US attorney for national security said the defendants worked in the United States, under the supervision and guidance of Saudi officials, and obtained private information Twitter users opposed to the Saudi government.

A third person, 30-year-old Saudi Ahmed al-Mutairi, was accused of being Riyadh's envoy to former employees and is suspected of helping the Zubara family flee the United States at the end of 2015 after the Twitter administration asked him questions for the first time.

A three-year jail sentence and a $ 250,000 fine, Abu Ammo faces an additional 20-year sentence and a $ 250,000 fine for destroying, changing or falsifying records, a Justice Ministry statement said.

The accusations point to an unusual public outcry towards Saudi Arabia, a US ally with good relations with US President Donald Trump, despite what Amnesty International calls its human rights restrictions and the "extrajudicial killing" of journalist Jamal Khashoggi.

The accusations also once again shed light on Silicon Valley technology companies on how they protect the private personal information they collect about their users, including from employees for whom there is no legitimate reason to share it.