Australian photographer Nigel Brenan went missing near Mogadishu
An Australian reporter and his Canadian colleague who have been missing in Somalia since Saturday have been named as Nigel Brenan and Amanda Lindhout.
Somalia's National Union of Journalists said they had been abducted along with a Somali reporter and their driver.
A spokesman for the transitional government told the AFP news agency he believed the two were in captivity but their whereabouts were unknown.
Abdi Haji Gobdon said the information ministry was following the situation.
The Union says it has information that the journalists are being held in the Somali capital Mogadishu.
They failed to return from a trip along with a Somali journalist Abdifatah Elmi and their driver named as Mahad.
Nigel Brennan and Amanda Lindhout are freelance journalists working for Western media organisations.
The alarm was raised on Saturday when a security official at their hotel in Mogadishu said they had not returned from a trip to visit displaced people outside the city.
The group had set off by road in the morning and had been due to return to their hotel by noon.
When they did not come back on time hotel staff contacted people at their intended destination but say they were told the journalists had not been seen there. We demand that those holding Abdifatah Mohammed Elmi Nigel Brenan and Amanda Lindhout free them unconditionally and immediately
Omar Faruk Osman NUSOJ Secretary General
In a statement released on its website The National Union of Somali Journalists (NUSOJ) says it "has been investigating the case of the abduction since it emerged" and is trying to discover the whereabouts of the journalists and their driver.
"No formal claim of responsibility was made and the motive for the kidnapping remains unknown... there have been no demands" the statement went on.
The NUSOJ said it received information on Sunday morning that the two Westerners and their Somali colleagues were being held by a militia in a north-eastern district of Mogadishu.
"It is not clear whether they are being held for political purposes bargaining chips or financial purposes" the NUSOJ said "but journalists who spoke on condition of anonymity for their security said the abduction seems [to be a] pre-planned attack."
The NUSOJ Secretary General Omar Faruk Osman said "we are appalled by this cruel abduction of journalists and call for the immediate release of our colleagues who are being held captive because of their noble work for the Somali people".
"We demand that those holding Abdifatah Mohammed Elmi Nigel Brenan and Amanda Lindhout free them unconditionally and immediately" he said adding "we are worried about their safety as we have had no contact with anybody saying they are holding three journalists and their driver."
Abdifatah Mohammed Elmi's father Mohamed Elmi is trying to find out how his son is but says he doesn't have any concrete information on the kidnappers or where his son may have been taken.
"Some of the information we are getting so far indicates that the journalists were kidnapped by freelance militias who want a ransom" Mr Elmi said.
Nigel Brenan's parents expressed their worries over their son's safety in a statement from Australia.
"We are deeply concerned that our son... may have gone missing near Mogadishu in Somalia yesterday. He is a freelance photographer who arrived in Kenya just over a week ago" the statement said. "We understand that the Australian government is making urgent contact with relevant Somali authorities as well as the Canadian French and British embassies to help locate Nigel." Somalia has been without an effective government since 1991 and journalists and humanitarian workers are frequently kidnapped.