War in Ethiopia's Tigray wrenches families apart

* Farmer describes fleeing amid violence and chaos

* Tigray refugees say many families split by fighting

By Seham Eloraby and Baz Ratner

UM RAKUBA, Sudan, Dec 4 (Reuters) - Ethiopian farmer Gebrahid Welderfael said he last saw his wife and 18-year-old daughter in the sewer in his village in the Tigray region where the family had taken shelter from explosions and gunfire.

When he returned with his younger children from a quick trip to their house to collect supplies, they were gone, lost in the chaos of a conflict in the northern region where government and rebellious Tigray forces have been fighting since Nov 4.

Unable to find them, the 45-year-old walked with his younger daughter and two young sons to the Um Rakuba camp across the border to Sudan, where more than 45,000 have fled the conflict.

Similar tales are told by other refugees. Mothers and wives say they lost their husbands, while old men, women and children have crossed the border not knowing the fate of relatives.

"When we escaped, there were people shouting 'mom', 'dad', children screaming," Welderfael said, sitting in a small hut which he built himself where he and his children sleep on rugs.

"People were shouting for help, my children were crying but I calmed them down and told them to run."

The fighting between Prime Minister Abiy Ahmed’s federal army and forces loyal to the region’s former ruling party, the Tigray People’s Liberation Front (TPLF) is believed to have killed thousands of people.

TPLF leaders, who enjoy strong popular support in Tigray, appear to have fled to surrounding mountains and say they have begun a guerrilla-style resistance.

Welderfael could not provide details of the fighting and said a communication blackout in Tigray meant he had been unable to reach his wife since. The blackout also means Reuters is unable to verify accounts from either side.

The farmer said his children sometimes have nightmares and frequently ask him where their mother has gone. "I keep giving them hope," he said, "that they're probably safe."

(writing by Ulf Laessing; editing by Philippa Fletcher)