Amnesty International, the UK-based rights group, has voiced concern over the arrest of nine people, including two journalists and two opposition party members, in Ethiopia on suspicion of terrorist offences.
Woubishet Taye, a deputy-editor for the weekly Awramba Times, and Reyot Alemu from the Feteh newspaper who were arrested on July 19 and 21, were among those detained.
Demelash Woldemikael, the assistant commissioner of Ethiopia's federal police, said: "The group was caught while plotting to sabotage electricity and telephone lines in an attempt to wreak havoc in the country.
"Further investigation has also revealed that they acted to recruit others to carry out terrorist activities with support from the Eritrean government and other anti-peace groups."
Demelash said the group will be charged upon completion of investigations.
The detentions prompted the media watchdogs the Committee to Protect Journalists (CPJ) and Reporters Without Borders (RSF) to call for their immediate release.
"The pretext of counter-terrorism being used to silence dissent, particularly among groups traditionally critical of the government such as political opposition parties and the private press is worrying," Michelle Kagari, Amnesty International's deputy Africa director, said on Thursday in a statement.
"The detainees must be granted full and prompt access to legal representatives and their families."
In a statement, the Paris-based RSF said: "The mystery surrounding their detention is unacceptable.
"These shady methods suggest a desire to stifle outspoken media and impose a news blackout on government abuses by scaring journalists and pressuring them to censor themselves on a regular basis."
Shimelis Kemal, a government spokesman, said their incarceration had no link with their political affiliation or their jobs.
"This has nothing to do with their reporting or political activity. They were arrested because they plotted to carry out terrorist activities and recruited others to join them," he said.
The US-based CPJ reported on June 24 that journalists covering the activities of Ethiopia's opposition figures, or those of the Ogadeb National Liberation Front (ONLF) rebels, have risked prosecution since the country's anti-terrorism law came into effect in 2009.
"The law criminalises any reporting authorities deem to 'encourage' or 'provide moral support' to groups and causes the government labels as 'terrorists'," Mohamed Keita and Tom Rhodes, CPJ Africa programme staff, reported on the CPJ blog.
"Ethiopia is a country whose relative stability in the troubled Horn of Africa region is in great part maintained by repression of dissent and ever-increasing restrictions on the freedom of the press.
"It receives praise and assistance for its participation in US counterterrorism in Somalia, but for Ethiopian journalists, reporting on terrorism [as defined by their government] without risking jail time has become too risky," the staff added.
The blog posted, entitled "In Ethiopia, anti-terrorism law chills reporting on security", reported that local journalists had revealed that it was only acceptable to write about terrorism if it was clearly denounced else "she or he is taking the risk of any interpretation".
'Risk of torture'
Amnesty International also warned on Thursday that some of the detainees may be at risk of torture.
The group are being held at Maikelawi – the Federal Police Crime Investigation and Forensic Department in Addis Ababa - which is reported to be under the command of the National Intelligence and Security Service.
"Maikelawi is infamous for the frequent use of torture against pre-trial detainees," Kagari said.
"It is troubling that the vaguely defined provisions of the anti-terrorism legislation are being used to suppress legitimate freedom of expression in Ethiopia."
Ethiopia and Eritrea have often traded tough rhetoric since a 1998-2000 border war.
Ethiopian Prime Minister Meles Zenawi regularly accuses Eritrean leader Issaias Afeworki of supporting opposition and rebel groups in Ethiopia.
Addis Ababa claims its northern neighbour is trying to destabilise the region by backing rebels, while also supporting Islamist fighters in Somalia.