The Saudi authorities are remaining tight-lipped about the identities of 10 men arrested on Friday on suspicion of funding insurgents outside the country.
Nine Saudis and a foreign national, reported to be from Morocco, were held in raids in Jeddah and Medina.
They were arrested for collecting money for "suspicious parties".
But a defence lawyer says the men are reformists with no links to terrorism. Newspaper reports and relatives described them as professional people.
They include lawyers and academics know for their reformist activities, according to reports in the Arab media.
The 10 - who include liberals and moderate Islamists - have in the past signed petitions condemning violence and calling for political reform.
BBC Middle East analyst Roger Hardy says some Saudis suspect the charge of funding terrorism to be a pretext - and that the 10 have been arrested for their political beliefs.
A lawyer representing four of the men says they were recently warned by the interior minister, Prince Nayef, to stop holding meetings and signing petitions.
The government said the men were suspected of illegally collecting donations and passing them on to what are described as "suspicious elements" outside the country.
An interior ministry statement said the money was being used to lure "the sons of the nation to disturbed places", which correspondents say was probably a reference to neighbouring Iraq.
Seven of the Saudis and the foreigner were arrested while meeting in Jeddah on Friday night. The other two were held in separate raids in Jeddah and Medina.
In recent years, Saudi Arabia has been responsible for a highly visible campaign to seek out militants sympathetic to al-Qaeda among its citizens.