By Guled Mohamed

NAIROBI (Reuters) - Nearly 20,000 civilians are fleeing violence in Somalia's capital Mogadishu every month with little hope of peace and stability in the Horn of Africa nation, a senior United Nations' official said on Thursday.

"The problem with Somalia is intractable ... The situation seems to be deteriorating. We don't see any improvement," Guillermo Bettocchi, head of the U.N. refugee agency for Somalia, told Reuters.

"Nowadays, an average of 20,000 people are leaving the city every month."

Up to one million of Somalia's total population of nine million are living as refugees after 17 years of conflict which took a new turn since early 2007 with an Islamist-led insurgency against the Ethiopian-backed government.

Most of the recent refugees are from the capital Mogadishu, where Iraq-style attacks are a near-daily occurrence.

Many parts of the capital are destroyed and deserted.

Somalia now has the world's largest group of internally displaced people, Bettocchi said, on a small corridor between Mogadishu and Afgoye town to the west where 200,000 are camped in "very difficult conditions."

Reliant on handouts, many live in makeshift shacks made from sticks, boxes and tattered clothes.

"I have never seen anything like Somalia in terms of the suffering of people," said Bettocchi, a 54-year-old Peruvian, with experience in various global hot-spots from Iraq to Sudan.

"NEGLECTED CRISIS"

Aid workers say Somalia's humanitarian crisis is one of the world's worst but is not receiving the attention it deserves. In Africa, it has been overshadowed by the conflict in Sudan's Darfur region.

"The situation in Somalia is not the forgotten crisis but the neglected crisis," Bettocchi said.

"In terms of effect on the people, it surpasses Darfur ... The consequences of the violence in Somalia are much worse."

Trying to escape violence and economic hardship at home, some 10,000 immigrants -- from Somalia and elsewhere in the Horn of Africa -- have fled from Somalia to Yemen this year. They go via the shark-infested Gulf of Aden on rickety boats owned by ruthless smugglers who often throw refugees overboard.

"In 2008 ... we have reports of 200 people who have drowned and died and we have reports of over 250 people who are missing. We don't know what happened to them," Bettocchi said.

He cited the example of an Ethiopian woman who gave birth unconscious on a boat only for the smugglers to throw her baby overboard before she came round.

"That kind of abuse is unacceptable," he added.

The U.N. official said smugglers were shifting their bases from Bosasso, a port in the relatively peaceful region of Puntland in north Somalia to Djibouti, which is nearer to Yemen, due to lower costs.