Index on Censorship condemns the arrest on Monday 13 June of human rights campaigner Nabeel Rajab in Bahrain. According to reports Rajab was charged on Tuesday 14 June with “publishing and broadcasting false news that undermines the prestige of the state” and detained for seven days.

Rajab, a former Freedom of Expression Award winner and a judge on this year’s awards, is one of the Gulf region’s most well-known human rights activists. Since the Bahraini uprising of 2011, he has been arrested on numerous occasions: he spent two years in jail between 2012 and 2014, and was arrested just months after his 2014 release for tweets in which he called Bahraini institutions “ideological incubators” for ISIS.

Rajab, president of the award-winning Bahrain Center for Human Rights (BCHR), and a member of the advisory committee of the Human Rights Watch Middle East division, spent three months in jail for the tweets. He was rearrested on Monday, according to the Bahrain Institute for Rights and Democracy. The reasons for the arrest were unclear.

“The harassment of Nabeel Rajab must stop. We call on the international community – and especially Bahrain’s close ally, the United Kingdom – to condemn this ongoing attempt to silence one of the region’s most highly respected human rights campaigners,” said Index chief executive Jodie Ginsberg.

Bahraini authorities have repeatedly targeted Rajab as well as other human rights campaigners and political activists. Last week, Zainab Al-Khawaja was forced into exile in Denmark. Abdulhadi Al-Khawaja, her father, is serving a life sentence for his calls for democracy in Bahraini society. Her sister, Maryam Al-Khawaja, has also been harassed by the authorities and has been exiled to Denmark.

Related: Bahrain continues to use arbitrary detention as a weapon to silence critics