Opposition groups in Kuwait say a leading political activist has been arrested on charges of criticizing the Gulf nation's ruler during protests.

The detention of former lawmaker Musallam al-Barrack is likely to raise tensions between Kuwait's ruling system and opposition factions led by Islamists, which seek to regain control of parliament in Dec. 1 elections.

Al-Barrack appeared late Monday on a pro-opposition TV station, Al-Youm, shortly before his arrest and urged for a major turnout at the next protest gathering planned for Sunday.

Kuwait has the most politically empowered parliament among Gulf Arab states and tolerates open criticism of government officials. But denouncing the ruling emir remains a red line.

Earlier this month, al-Barrack warned the emir to avoid "autocratic rule" and not amend election rules.