By Tsegaye Tadesse

ADDIS ABABA, April 10 (Reuters) - Ethiopia's biggest opposition party in parliament pulled out of a round of local elections due next week, accusing Prime Minister Meles Zenawi's government of intimidating its supporters.

The United Ethiopian Democratic Forces said the Horn of Africa nation's police and electoral board had failed to address its complaints of electoral violations before Sunday's polls for local councils, UEDF Chairman Beyene Petros said.

"Since there was no level field for a democratic election and our candidates were beaten, arrested and their property confiscated by cadres of the ruling party, we have decided to pull out of the local council elections," Beyene said on Thursday.

Meles' government said it regretted UEDF's choice.

"It is unfortunate that UEDF is withdrawing from a competitive election," said Bereket Simon, special adviser to Meles. "The ruling party has tried to accommodate all their wishes and has gone an extra mile to ensure their participation."

UEDF commands 50 seats in the 547-member Ethiopian parliament and had been planning to field about 20,000 candidates for various local-level posts.

By contrast, Meles' Ethiopian Peoples Revolutionary Democratic Front has some 4 million candidates running.

Meles' once-strong democratic credentials were seriously tarnished after national polls in 2005 in which tens of thousands of opposition backers were jailed and more than 200 people killed in clashes with security forces.

The opposition made its greatest-ever gains in the polls, which were Ethiopia's third true multi-party elections.

But Meles' government charged dozens of opposition leaders with genocide and inciting violence, and they were convicted last year and pardoned almost instantaneously.

The effect, analysts say, was to seriously fragment the opposition's cohesion. (For full Reuters Africa coverage and to have your say on the top issues, visit: http://africa.reuters.com/ ) (Writing by Bryson Hull; Editing by Mary Gabriel)