A Gulf rights group and a Kuwaiti MP on Sunday criticised the arrest of a member of the Gulf state's ruling family for expressing "political views" deemed offensive.
"Freedom for Sheikh Meshaal al-Malek al-Sabah who was arrested by the state security police," the Gulf Forum for Civil Societies, an organisation of liberal activists, said on its Twitter account.
It said Sheikh Meshaal was arrested "because of his courageous views that opposed the policies of the Kuwaiti ruling family."
Islamist opposition MP Waleed al-Tabtabai deplored the arrest of Sheikh Meshaal "for his political views," and criticised what he called the return of a government policy of harassing activists who use social media.
Tabtabai said Sheikh Meshaal has been detained by the secret service for the past three days. Activists said he was arrested on Thursday on his return from Saudi Arabia where he met the governor of Riyadh.
So far, there has been no official comment on his arrest.
Sheikh Meshaal is a member of the Al-Sabah family which has ruled the oil-rich emirate for the past 250 years without challenge.
In tweets he wrote over the past few days, he said he will contest the next parliamentary election to become the first royal in Kuwait to do so, and also vowed that if he becomes an MP, he would expose corruption among top officials.
He also complained that the Kuwaiti constitution entrusts power to only one branch of the Al-Sabah family -- the descendants of Mubarak Al-Kabeer who ruled Kuwait from 1896 to 1915.
Sheikh Meshaal, who is not descended from Mubarak Al-Kabeer, called for the constitution to be amended and the introduction of political reforms.