The United States in a statement on Thursday said that too many deaths of journalists are going unpunished in Somalia, while media and rights groups condemned Somalia's information minister for harassing reporters.
Britain also expressed its alarm at Abdulle's killing.
"This shocking murder tragically underlines the ongoing struggle throughout the world for press freedom, and I offer my condolences to . . . Abdulle's family and friends," Britain's Africa minister, Henry Bellingham, said. "It is particularly distressing to see further violence against journalists in Somalia."
Journalist Abdullahi Ahmed recalled staring at his phone in fear recently when an unregistered number kept calling him. Many Somalian journalists reported similar problems.
"They call you and threaten you," said Ahmed, a TV reporter. "You have to sometimes abandon answering unknown calls. A call you think is from an ordinary caller can turn out to be a threatening call. It's a stressful situation."
The day after Abdulle's killing in the northern town of Galkayo, dozens of worried journalists met in Mogadishu to commemorate World Press Freedom Day.
"We are meeting at a difficult time," said Abdirashid Abdulle Abikar, a leader of the journalists' union. "Our friends are leaving the country and many are still committed to continue their work despite the risks."
African Union troops have pushed al-Shabab militants out of the capital, which is now safer than in recent years. Despite the general safety, journalists have become a common target.
Amnesty International noted that Abdulle was the second journalist killed in Galkayo in the last six months. It said the Somalian government has failed to bring anyone to justice for the killings of at least 28 journalists since 2007.