Lawyers for the 31 Omani Islamists pleaded their clients' innocence as their trial resumed on Monday in the capital, Muscat.
Three lawyers defending 12 of the group said they had merely sought to promote the teachings of the sultanate's majority Ibadi sect in the face of "external currents".
They said their clients' possession of weapons was in keeping with Omani norms and that the worst they can be accused of is holding firearms without a licence.
The trial opened a week ago with the accused, who were arrested in January, appearing before the State Security Court in batches over three consecutive days.
The defendants have pleaded not guilty to the charge of plotting to overthrow the government by force, although some of them expressed "regret" and asked Sultan Qaboos bin Said Al Said to pardon them.
Sultan Qaboos was approached
by some defendants for pardon
Ahead of Monday's session, police showed reporters some of the weapons seized with the accused, including around 40 Kalashnikov rifles, nine pistols and a large quantity of ammunition.
A lawyer with one of the firms defending the suspects earlier said it was not clear when a verdict would be delivered, but added that those convicted would have the right to appeal to the Supreme Court and then to the Omani ruler.
The lawyer said the prosecution had sought the death penalty for all suspects charged with subversion, but he doubted the sentence would be imposed.
State's red line
The prosecutor at Monday's hearing asked the judge to rule as his court sees fit.
"Serving the [Ibadi] sect does not require forming a secret organisation, especially since the state serves the Ibadi sect as it does other Islamic sects," he said.
The state-run Oman Daily Observer warned that "fiddling with the state's security is a 'red line' ... . Preaching religion is achieved by prudence and good advice, not by force. Likewise, the call for reform and guidance to the path of piety does not require underground measures or secret meetings."
"Serving the [Ibadi]
sect does not require forming a secret organisation, especially since the state serves the Ibadi sect as it does other Islamic sects"
The prosecution says the secret organisation to which the accused belong was first formed in 1982.
It has a public arm which organises pilgrimages and youth summer camps, and an underground wing that strives for the establishment of an imamate in Oman in accordance with the teachings of their faith, according to the charge sheet.
An offshoot of a dissident Shia sect, the Ibadis are named after their founder, Abd Allah bin Ibadh al-Maqissi, originally from Ibadh in Saudi Arabia. The faith was introduced to Oman in the eighth century.
Unconfirmed reports at the time of the arrests said the group was suspected of planning attacks on the Muscat festival, a month-long trade and cultural event spanning part of January and February, as well as commercial centres and oil installations.