Kuwait plunged into political turmoil on Friday after the public prosecution ordered the detention of three former opposition MPs for three days with more arrests expected.

The three -- Falah al-Sawwagh, Bader al-Dahum and Khaled al-Tahus -- were questioned for nine hours on accusations of undermining the status of Kuwait's ruler before being taken into custody around midnight, defence lawyer Mohammad al-Jumaih said.

The prosecutor also extended the detention for three more days of four opposition activists arrested on Monday during clashes between police and protesters following a huge rally.

The move came as hundreds of supporters of the Islamist and nationalist-led opposition and former lawmakers gathered outside the Palace of Justice in the capital, Kuwait City, in solidarity with the ex-MPs and activists.

Breaking decades-old taboos, speakers directly addressed Emir Sheikh Sabah al-Ahmad Al-Sabah, warning him that any amendment to the electoral law could lead to street protests and chaos.

They also warned Kuwait was becoming an autocratic state, and insisted they would oppose that.

The emirate embraced parliamentary democracy half a century ago, but it is illegal under the constitution to criticise the emir who enjoys extensive authority and must be from the Al-Sabah ruling family, in power for over 250 years.

Kuwait, an OPEC member which says it sits on 20 percent of global oil reserves and has more than $400 billion of surpluses, has been in a virtual limbo since June 20 when the top court anulled an opposition-dominated parliament.

The historical court verdict also reinstated the pro-government parliament elected in 2009 after it was dissolved in December following street protests and corruption allegations.

The house however was dissolved again two weeks ago but the government has so far failed to set a date for next elections amid allegations it is planning to change the electoral law to manipulate the polls results.