Shaikh Hamad al-Ali was detained for 21 days pending an investigation, his lawyer Fahd Kumaikh said on Sunday.
Kumaikh said his client was called on Saturday by state security and briefly interrogated before being referred to the public prosecution.
The lawyer added he was not informed of the charges on which the cleric was questioned because he was barred from attending the interrogation.
"I was not allowed to attend the interrogation, which is a violation of Kuwaiti law, but I was told by legal sources that the cleric was detained for 21 days," Kumaikh said.
Legal sources, however, said the cleric was being questioned over his calls for holy war.
Hamad, 50, was first questioned by the public prosecution on 31 August on charges that he had called for jihad against US forces in Iraq and was freed without bail.
The cleric was handed a two-year suspended jail sentence last June for publicly opposing Kuwait's support for the US-led war on Iraq in March 2003, which toppled President Saddam Hussein.
The verdict was based on Hamad's fatwa, or religious edict, which stated that "any backing by a Muslim country of foreign troops in attacking another Muslim state contravenes Islamic teachings," in reference to Kuwait's support for the invasion of Iraq.
Hamad was the secretary-general of the Salafi Movement for five years until 2000.
He was stopped last month by the Ministry of Islamic Affairs from delivering weekly sermons at a government mosque.
Kuwait, which was invaded by Saddam's army in August 1990 and occupied for seven months, served as the main launch pad for the US-led war.