Ethiopia’s Prime Minister Abiy Ahmed rejected U.S. calls for a unilateral ceasefire in the northern Tigray region and dismissed allegations of ethnic cleansing, according to a senior U.S. lawmaker sent to Addis Ababa by President Joe Biden.

But Democratic Senator Chris Coons, recounting his talks with Abiy last weekend in the Ethiopian capital, also praised the prime minister for publicly acknowledging for the first time that troops from neighboring Eritrea entered Tigray during the five-month-old conflict, after months of denials.

Abiy also pledged this week following Coons’ visit that any soldiers who carry out human rights violations will be punished.

“I’m encouraged by that. But the prime minister has made commitments before and fallen short on delivering. So I think it’s critical that we stay engaged,” Coons told reporters.

Ethiopia’s mission to the United Nations in New York did not immediately respond to a request for comment on Coons’ remarks.

Fighting erupted in Tigray after forces loyal to the then-governing party there - the Tigray People’s Liberation Front (TPLF) - attacked army bases across the region overnight and in the early hours of Nov. 4.

The attacks initially overwhelmed the federal military, which mounted a counter-offensive alongside Eritrean soldiers and forces from the neighboring region of Amhara.

The TPLF, which dominated Ethiopia’s government for nearly three decades until Abiy came to power in 2018, has long been an archenemy of Eritrea.

The violence in Tigray has killed thousands of people and forced hundreds of thousands from their homes in the mountainous region of about 5 million.

Coons said Abiy denied there had been a forced relocation of Tigrayans from west Tigray, saying the prime minister told him there “had been and would be no ethnic cleansing.”

“He pushed back really hard on any attempt by me to characterize this as an ethnic conflict and insisted it was a conflict against the TPLF as a political actor and a political party that had engaged in an attack on federal forces,” Coons said.

U.S. Secretary of State Antony Blinken said earlier this month that he wanted to see Eritrean forces and those from the Amhara region replaced in Tigray by security forces that would respect human rights and not “commit acts of ethnic cleansing.” Ethiopia rejected Blinken’s allegation.

Coons said he pressed Abiy during both days of their meetings on March 20 and 21 to declare a ceasefire but Abiy declined, arguing that the fighting had largely stopped and the situation by then amounted to “a law enforcement action where they are pursuing a few TPLF senior leaders.”

“So his response was that a ceasefire is not necessary,” Coons said, describing it as “a persistent point of disagreement” between them.

In a speech to parliament on Tuesday, Abiy acknowledged for the first time that atrocities including rape had been committed during the fighting, and he said perpetrators would be punished. But he said some of the accounts were overblown.

“There were atrocities that were committed in Tigray region. Taking the exaggerations, the propaganda, and the lies aside, reports indicate that atrocities were being committed by raping women and looting properties,” Abiy told lawmakers.

The United Nations said on Thursday more than 500 rape cases have been reported to five clinics in Tigray, including “men being forced to rape their own family members under the threat of violence”, and that the actual numbers were likely to be far higher.