(Adds AU quotes on peacekeepers, paragraphs 20-22) By Aweys Yusuf and Abdi Sheikh MOGADISHU, Sept 18 (Reuters) - Somalia's independent Shabelle media house said government troops surrounded its Mogadishu office on Tuesday and opened fire at the building, wounding a security guard. The interim government's relations with independent media houses have been rocky since it and its Ethiopian army backers routed an Islamist movement from the capital over the New Year. Government officials declined to comment on the incident, which came after security forces arrested 18 staff at the broadcaster on Saturday. "We do not know why they are targeting us," Shabelle acting manager Jafar Kukay told Reuters by telephone from the office. "On Saturday, they said a grenade was thrown at them from the Shabelle building. But now I do not know what they want." He said most of the staff had managed to flee the compound during a lull after two hours of shooting. "We are now off-air. A security guard was wounded," he said. Shabelle is involved in radio news, news websites and news photographs. Islamist insurgents have been blamed for a series of roadside bombs, assassinations and suicide blasts since the government won back control, and top officials have accused local broadcasters of bias, stoking tension, backing terrorists and opposing the government. Shabelle and two other independent outlets, HornAfrik and IQK Koranic Radio, were briefly banned and taken off air in January and June, prompting criticism from press watchdogs. In the latest dispute, security forces stormed the Shabelle office in central Mogadishu on Saturday, taking 18 employees to a police station for questioning. They were later released. INTIMIDATION The Committee to Protect Journalists on Tuesday accused the interim administration -- the impoverished country's 14th attempt at central rule -- of persecuting reporters. "Many Mogadishu-based journalists have been forced to flee the country due to the ongoing intimidation of journalists," Joel Simon, the CPJ's executive director, said in a statement. The CPJ says six Somali reporters have been killed so far this year in direct relation to their work, making it the second deadliest nation for journalists after Iraq. Last month the co-founder of HornAfrik, Ali Iman Sharmarke, was killed by a landmine in the capital while driving back from the funeral of a murdered journalist colleague. Also on Tuesday, Somalia's interior minister, Mohamed Mahamud Guled, called for help to avert a humanitarian disaster. "A humanitarian catastrophe is imminent if the international community does not respond soon," he told a news conference. "We ask the donor countries and the world to help Somalia before the country faces another catastrophe like the one in 1992." Hundreds of thousands died in a wartime famine in 1992, prompting the U.N. military effort "Operation Restore Hope". Last week, the U.N. children's agency UNICEF said child malnutrition had now reached critical levels in central and southern regions that were once the country's breadbasket. It blamed continuing violence and lack of access for aid workers. In Addis Ababa on Tuesday, a senior African Union (AU) official welcomed a call this week by Somali government leaders for U.N. peacekeepers to replace AU troops already there. "The sooner the better. It would be most welcome if the U.N. takes over responsibility for ensuring peace and security," Geofrey Mugumya, AU peace and security director, told Reuters. "The move could also solve the AU's financial problems." (Additional reporting by Tsegaye Tadesse in Addis Ababa)
