Ethiopia’s ruling party celebrated a clean sweep victory in parliament Monday with the announcement of last month’s election results.

The Ethiopian People’s Revolutionary Democratic Front (EPRDF) of Prime Minister Hailemariam Desalegn secured all 547 parliamentary seats, taking the one seat held by an opposition MP in the previous chamber, said Merga Bekana, chairman of the electoral board.

The EPRDF, in power in Africa’s second-most populous nation for over two decades, was widely expected to secure a near clean sweep of parliament, and the outgoing chamber had just one opposition MP.

African Union observers said the polls passed off without incident, but the opposition alleged the government had used authoritarian tactics to guarantee victory.

Government spokesman Shimeles Kemal has said the party’s success was the result of Ethiopia’s economic advances. “Voters have credited the ruling party for the economic progress it introduced in the country,” he told AFP.

“They want the continuation of this policy. In view of the weak, fragmented opposition and the lack of viable alternative, it was very likely that the ruling party would win in a landslide.”

According to the electoral board, the EPRDF also took back the only seat that was held by the opposition, securing all 23 seats in the capital Addis Ababa.

Ethiopia, whose 1984 famine triggered a major global fundraising effort, has experienced near-double-digit economic growth and huge infrastructure investment — making the country one of Africa’s top-performing economies and a magnet for foreign investment.

It also remains a favourite of key international donors, despite concerns over human rights, as a bastion of stability in an otherwise troubled region.

Ethiopia’s former Marxist rebel-turned-leader Meles Zenawi, who died in 2012, was succeeded by Mr Desalegn, who has said he is committed to opening up the country’s political system to allow more space for opposition parties.

Freedom of speech

But rights groups routinely accuse Ethiopia of clamping down on opposition supporters and journalists, and of using anti-terrorism laws to silence dissent and jail critics. Activists have said the polls were not be free or fair due to a lack of freedom of speech.

The United States, which enjoys close security cooperation with Ethiopia, also said it remained “deeply concerned by continued restrictions on civil society, media, opposition parties, and independent voices and views.”

US President Barack Obama will in late July become the first sitting American leader to visit Ethiopia. The European Union has also said that true democracy had yet to take root in Ethiopia.

The African Union deployed 59 observers for the May 24 polls, but European Union and Carter Centre observers, who were present for the 2010 vote, were not invited.