Yemen's Houthi rebels have arrested a prominent activist who used social media to document the war that has ravaged his country.
On August 12, Hisham al-Omeisy tweeted to his 23,700 followers: "Armed goons backed by corrupt officials are forcefully taking real estate in Sanaa. They just showed up at my door."
He has not been seen on Twitter since.
The 38-year-old father of two was reportedly captured on Monday in the capital, Sanaa, by more than a dozen armed security officers from the National Security Bureau, rights group Amnesty International said on Friday.
"Hisham al-Omeisy has been detained without charge or a court appearance in breach of Yemen's constitution, which requires anybody arrested to be presented in court within 24 hours," said Samah Hadid, director of campaigns for Amnesty International in the Middle-East.
"This detention illustrates the lengths to which local Houthi-Saleh authorities' are willing to go to silence peaceful activists. Hisham al-Omeisy is a prisoner of conscience, whose only 'crime' is peacefully exercising his right to freedom of expression, and he must be released immediately." Hadid said in a statement.
New York-based rights group, Human Rights Watch, also made a similar appeal for the release of 38-year-old Omeisy on Friday.
"Yemen more than ever needs activists like Hisham al-Omeisy to bring attention to the devastation that war, famine, and disease have wrought on the country and its people," Sarah Leah Whitson, the group's Middle East director said.
"Houthi authorities should immediately release Omeisy and return him safely to his family." Whitson added.
'Let's raise hell for his release'
Several social media users demanded Omeisy's release.
Investigative journalist Iona Craig wrote on Twitter: "Hisham is not only a friend but an essential voice for Yemenis. We are all deeply concerned for his wellbeing."
Craig explained that many of his friends had earlier kept quiet about Omeisy's detention at his family's request.
Osamah Al-Rawhani, programme director at Sanaa Centre, a Yemen-based think-tank, tweeted: "Let's raise hell for the release of @omeisy ... Houthis must stop their violations against human rights and freedoms."
Jeremy Schahill, a journalist, said Omeisy "regularly live tweets US-backed Saudi bombings and is also critical of Houthi forces as well. Now he has been kidnapped".
Yemen, which is on the southern edge of the Arabian Peninsula, has been engulfed in civil war since September 2014, when Houthi Shia rebels swept into the capital and overthrew President Abd-Rabbu Mansour Hadi's internationally recognised government.
In March 2015, the Saudi-led coalition began a campaign against Houthi forces allied with overthrown President Ali Abdullah Saleh in support of Hadi's government.
Since then, the Iranian-backed Houthis have been dislodged from most of the south, but remain in control of Sanaa and much of the north.
Source: Al Jazeera and news agencies