ADDIS ABABA, September 7, 2011 (AFP) - Ethiopia charged two Swedish journalists with terrorism Wednesday, the first formal charges levelled against them since their July 1 arrest near Ethiopia's border with Somalia.

"The two journalists are accused of being engaged in a terrorist activity in violation of the new anti-terrorism statute of Ethiopia," said Ethiopian government spokesman Shimeles Kemal.

Photographer Johan Persson and reporter Martin Schibbye, both freelancers, have been held in jail since they were arrested with Ogaden National Liberation Front (ONLF) rebels, who are opposed to the Ethiopian government.

Fighting broke out between the rebels and Ethiopian troops, killing 15 and injuring six, including the journalists, who suffered gunshot wounds.

Sweden said they were worried about the charges against the pair.

"The two journalists were on spot on a journalistic mission and we have not had reason to question their claim," Swedish foreign ministry spokesperson Anders Jorle told AFP by telephone from Stockholm.

"It is worrying us that the case has been brought to a charge against the journalists."

The Swedes are also accused of abetting a terrorist group and entering the country illegally from Somalia without permission, Shimeles said.

"They are accused of abetting and rendering professional assistance to terrorists," he said.

"The third count relates to their entering into a sovereign state without a valid visa or lawful permission."

The Swedes who appeared in court on Tuesday in Addis Ababa with two Ethiopians accused of being members of the ONLF, who were also charged with terrorist offences.

During the hearing, the public prosecutor showed the court video footage he said showed the Swedes receiving weapons training from ONLF gunmen.

The maximum sentence for commissioning or planning terrorist activities under Ethiopian law is life in prison.

International press freedom watchdogs have condemned the arrests of the journalists.

Since its formation in 1984, the ONLF has been fighting for the independence of the remote southeastern Ogaden, which is populated mainly by ethnic Somalis and has been marginalised by the Addis Ababa regime.

Ethiopia last month arrested 31 people, including prominent opposition party members, on terrorism-related charges and being members of the Oromo Liberation Front (OLF), another rebel group battling the government.