Kuwait authorities have detained several online activists allegedly for comments deemed offensive to Saudi Arabia's late King Abdullah, a rights group and activists said Thursday.

Secret police late Wednesday arrested prominent rights and online activist Mohammad al-Ajmi outside his home for “unknown reasons,” the National Committee for Monitoring Violations, an independent rights group of which Ajmi is a member, said on its Twitter account.

Online activists and former MPs said on Twitter that Ajmi was being held for questioning over Tweets he made on Saudi Arabia.

Nawaf al-Hendal, a leading rights activist, said at least four others had been detained by state security for tweets deemed offensive to King Abdullah who died on Friday.

Hendal, currently in Geneva, also said on his Twitter account that arrest warrants have been issued against him and five other tweeters for the same reason.

The Gulf Centre for Human Rights, an independent body, said Hendal was being “targeted in order to intimidate him and others from working as defenders of human rights. “There was no word on the arrests from the interior ministry and the public prosecutor has not announced any charges.

Kuwait has cracked down on activists for making comments seen as critical of the oil-rich state's ruler and other Arab leaders, especially in the Gulf.

Former liberal MP Saleh al-Mulla was detained for five days earlier this month for tweets deemed offensive to Egyptian President Abdul Fattah al-Sisi during a two-day visit to Kuwait.

He is to stand trial on February 15.

And Shia MP Abdulhameed Dashti is facing trial for criticising Bahrain leaders, while former Islamist MP Mubarak al-Duwailah was questioned over comments critical of Abu Dhabi's rulers.

Since a political crisis in June 2012, Kuwaiti authorities have ramped up efforts to curtail dissent.

Courts have sentenced politicians, online activists and journalists to prison terms for exercising free speech rights, Human Rights Watch said this month.