ADDIS ABABA, June 17 (Reuters) - Ethiopia is preparing for national and regional parliamentary elections on Monday that Prime Minister Abiy Ahmed has said will be the country"s first free and fair polls after decades of repressive rule. But voting has been delayed in 110 out of 547 constituencies because of violent conflicts and logistical problems and some opposition parties are boycotting the elections over what they describe as harassment of their members. One candidate is contesting the election from jail. Abiy won international plaudits and a Nobel Peace Prize for democratic reforms and for ending two decades of hostilities with neighbouring Eritrea when he was named head of Ethiopia"s governing coalition in 2018. Within months of taking office, he unbanned opposition parties, released tens of thousands of political prisoners, and took steps to open up one of Africa"s last untapped markets. He now faces mounting international pressure over a war in the northern Tigray region and accusations from rights groups that his government is rolling back some new freedoms, which it denies. Abiy"s spokesperson Billene Seyoum declined to comment. read more Monday"s elections will be the first test of voter support for Abiy"s government. Abiy said on Twitter this week the polls would be "the nation"s first attempt at free and fair elections." Previous elections were tainted by accusations of vote rigging. In 2015, the ruling coalition and its allies won every parliamentary seat. Some 37 million of Ethiopia"s 109 million people have registered to cast ballots, although some will have to wait until a second round of voting in September. No date has been set for voting in Tigray, where Ethiopia"s military has been fighting the region"s former governing party, the Tigray People"s Liberation Front (TPLF), since November. OPPOSITION BOYCOTT Abiy"s Prosperity Party remains the front-runner in a field of 46 parties vying for parliamentary seats. The opposition is fragmented between smaller, mostly ethnically-based parties. Merera Gudina, an ethnic Oromo and head of the Oromo Federalist Congress, was initially supportive of Abiy"s reform agenda. But he said his party would boycott the elections after regional security forces shut down 203 of their offices in Oromiya region during the last year, leaving only three open. Merera, a former political prisoner, said thousands are detained. "Our hope for free, fair, credible elections (is) dashed." Gizachew Gebisa, deputy spokesperson for the Oromiya regional administration, referred questions to regional police commissioner Ararsa Merdasa, who did not respond. The leader of another party, Balderas for Genuine Democracy, is jailed on terrorism charges, which he denies. Judges ruled in May that Eskinder Nega, an ethnic Amhara, could stand for parliament while in prison. Others are more optimistic about next week"s vote. "Nobody expects this to be 100% perfect. But we believe that this country needs a new start," said Birhanu Nega, whose Ethiopian Citizens for Social Justice party (Ezema) tries to transcend ethnic power blocs, although it has struggled to attract support outside urban centres. Abiy created the Prosperity Party in 2019 by uniting three out of the four ethnically based parties in the governing coalition, along with smaller regional parties, into one national party. The TPLF, which dominated the governing coalition for nearly three decades before Abiy came to power, refused to join. It accused him of centralising power at the expense of Ethiopia"s ethnically-based regions, which he denies. The elections were originally scheduled for August 2020, but Abiy postponed them citing the COVID-19 pandemic. The TPLF held elections in Tigray anyway, setting it on a collision course with the government. The fighting in Tigray has killed thousands and displaced more than 2 million. Last week, the United Nations warned of famine conditions in some areas. read more Abiy told parliament in March that reports of abuses there, including gang rapes and mass killings, were "exaggerated". However, he said abuses would be investigated and perpetrators brought to justice. read more The attorney general said last month more than 50 soldiers were on trial for rape or killing civilians, but has given no details. read more Violence has also flared in other regions, where ethnic power brokers seized on the political opening under Abiy to flex their muscles. Hundreds have died in clashes on the border between Oromiya and Amhara, Ethiopia"s two most populous regions. read more Asheber Aboneh, a 32-year-old engineer from Oromiya, said he"d vote for Abiy anyway "because a known devil is better than the unknown angel."