Fighting between Ethiopia's military and militiamen in the Amhara region has killed at least 183 people, the UN human rights office said on Tuesday, providing the most comprehensive independent death toll to date of the month-long conflict.

More than 1 000 people have been arrested nationwide, many of them reported to be young people of ethnic Amhara origin, under a state of emergency the government decreed to respond to the violence, the UN added in a statement.

Ethiopia's government spokesperson did not immediately respond to a request for comment.

The conflict has been fuelled by accusations among many in Amhara, Ethiopia's second most populous region, that the government is trying to undermine its security. The government denies the accusation.

Government forces reclaimed major towns and cities across the region earlier this month after initially being chased out by the militiamen, but the conflict has ground on.

"With federal forces reasserting their presence in certain towns and Fano militias reportedly retreating into rural areas, we call on all actors to stop killings, other violations and abuses," the UN statement said.

At least four people were killed in fresh fighting that erupted in the town of Debre Tabor on Sunday, two doctors said.

The clashes broke out about a week after Ethiopia's military entered the town, one of the doctors said. Both spoke on condition of anonymity for safety reasons.

One of the doctors said he had seen the bodies of four people killed in the clashes and many wounded, including his father-in-law, who he said was shot in the chest by an unknown gunman near his house.

The other doctor said at least seven people had died - three civilians and four police officers, who were fighting in support of the military.