ADDIS ABABA, Ethiopia — The Ethiopian government has rejected a call by human rights groups for an investigation into “police violence” during post-election unrest that left at least 27 people dead.

Most shops remained closed Friday and taxi drivers stayed off the streets for a second day in a strike called to protest against a government crackdown on the political opposition after the disputed elections.

Amnesty accused police of using live ammunition and beating mainly peaceful protesters. It did though acknowledge that some demonstrators threw stones.

“We call on the Ethiopian government to halt the police violence and set up an independent and impartial commission of inquiry,” Kolawole Olaniyan, the group’s Africa director, told Reuters.

The rights group estimated that at least 100 people had been injured in the clashes and up to 1,500 students and other protesters were at risk of torture after being arrested in Addis Ababa and other towns where rallies took place.

The European Union has also condemned Ethiopia’s tough line on the opposition, and concern at the situation has been expressed by the United States and the United Nations.

Ethiopia’s Information Minister Bereket Simon said though that opposition political parties should be held responsible for the violence and that their leaders may face criminal charges.

“Their objective was to undermine the electoral system and overthrow the government,” Bereket told The Associated Press.

“If anyone can stabilize this situation, it is the opposition, attention should be focused on them.”

The violence on Wednesday flared after weeks of opposition accusations that the ruling party had intimidated voters and rigged the polls to hold on to power in the strategic Horn of Africa nation.

Some opposition leaders were being kept at their homes, party sources and European Union observers told Reuters.

“The mission has conveyed to the government its condemnation of the house arrests and other harassment and threatening measures imposed on the opposition,” EU chief observer Ana Gomez said.

Prime Minister Meles Zenawi’s Ethiopian People’s Revolutionary Democratic Front (EPRDF) has ruled since 1991, when his guerrilla army deposed former military ruler Haile Mariam Mengistu.

Rejecting accusations of blame in the violence, the main opposition Coalition for Unity and Democracy (CUD) said the clashes were spontaneous.

The protests erupted despite Prime Minister Meles Zenawi’s move to ban demonstrations immediately after the May 15 legislative election.

Preliminary results from the election board showed the ruling party and its allies have enough seats to form the next government in the nation of 72 million people, the continent’s top coffee producer.

Opposition parties say there was widespread fraud and intimidation, charges the ruling party denies. Official results are due on July 8.

The elections had been seen as a test of Meles’ commitment to reform his sometimes authoritarian regime, analysts said.

Before questions surfaced about the count, EU observers had called the campaign and voting “the most genuinely competitive elections the country has experienced,” despite some human rights violations.

But opposition and ruling parties have alleged that gunmen intimidated voters, people were forced to vote for certain parties, ballot boxes were stuffed or disappeared, and the number of ballots in some constituencies exceeded the number of registered voters.

Wednesday’s killings were the worst in Addis Ababa since police and security guards killed 41 people during April 2001 riots that followed a wave of student protests.