Thirty Islamists have gone on trial at a state security court in the UAE, accused of illegally setting up a branch of the Muslim Brotherhood.
The 20 Egyptians and 10 Emiratis are also charged with stealing secrets from the security services and collecting donations without permission.
The defendants deny all the charges and allege they were tortured in detention.
In July, another 69 Islamists were found guilty of attempting to overthrow the country's political system.
They were sentenced to prison terms of up to 10 years.
Several of those convicted are among the 10 Emiratis who went on trial at a state security court in Abu Dhabi on Tuesday, including the human rights defender and lawyer Dr Mohamed al-Mansoori.
Among the 20 Egyptian defendants are three medical doctors, including Ali Ahmed and Mohammed Abdul Monem. Six of the Egyptians are being tried in absentia.
The defendants are said to be linked to an Emirati Islamist political society, al-Islah, which prosecutors assert is a branch of the Egypt-based Muslim Brotherhood.
Al-Islah says it favours peaceful reform and denies ties to the Brotherhood, which is outlawed in the Gulf state.
Like many of those convicted in July, the defendants say the UAE authorities subjected them to torture in detention and denied them access to legal assistance for many months.
At the trial, the judge appointed a three-member medical committee to carry out tests on some defendants to help investigate their claims of abuses, the state news agency WAM reported. Proceedings were then adjourned until 12 November.
The UK-based Emirates Centre for Human Rights had earlier complained that the authorities had failed to investigate or acknowledge what it called the "credible" allegations of torture.
"The fear is that this is another trial where defendants are being tried solely for their political beliefs," said its director, Rori Donaghy.
On Monday, Human Rights Watch warned that July's court judgement raised serious concerns about the new trail and called into question the ability of the UAE's judicial system to uphold basic rights of free speech and peaceful association.
The US-based group said the only evidence that suggested any intention by the 69 to overthrow the government had been an alleged confession by one defendant, who subsequently denied all charges in court.
"The court's judgment exposes the rank injustice of the convictions," said Joe Stork, HRW's deputy Middle East director. "Aside from one apparently coerced confession, the judgment describes a political society advocating social justice through peaceful political reform."
The rise of the Brotherhood in Egypt after the 2011 revolution alarmed most Gulf Arab states, including the UAE. After the Egyptian military ousted President Mohammed Morsi, a member of the Islamist movement, the UAE provided the interim government with $3bn of financial support.