Rebel forces from Ethiopia's war-torn Tigray on Friday rebuffed US calls to leave neighbouring regions, one day after they seized famed UNESCO heritage site Lalibela.

"Nothing of the sort is going to happen unless the blockade is lifted," said Getachew Reda, spokesman for the Tigray People's Liberation Front (TPLF), referring to restrictions on humanitarian access.

Northern Ethiopia has been wracked by conflict since last November, when Prime Minister Abiy Ahmed sent troops to topple the TPLF, the ruling party of Tigray which dominated national politics for nearly three decades before Abiy took office in 2018.

The church of St. George is one of the rock-hewn treasures of Lalibela, a UNESCO World Heritage Site
The church of St. George is one of the rock-hewn treasures of Lalibela, a UNESCO World Heritage Site AFP / EDUARDO SOTERAS

The move came in response to TPLF attacks on army camps, Abiy said.

But while Abiy promised victory would be swift, the war took a stunning turn in June when pro-TPLF forces recaptured the Tigray capital Mekele and the Ethiopian army largely withdrew.

Since then the TPLF has pressed east into the neighbouring Afar region and south into Amhara.

Woman harvests roses in a greenhouse at the ET Highland Flora flower farm just outside Ethiopian capital, Addis Ababa,
Woman harvests roses in a greenhouse at the ET Highland Flora flower farm just outside Ethiopian capital, Addis Ababa. Reuters

Top US officials including US aid chief Samantha Power, who visited Ethiopia this week, have called on the TPLF to withdraw and for all sides to cease hostilities and focus instead on addressing the humanitarian "catastrophe" in Tigray.

On Thursday, TPLF fighters entered Lalibela without a fight, as security forces withdrew ahead of their advance, residents told AFP.

The move prompted Amhara's government to warn that the TPLF was pressing "deep" into Amhara territory and to hint at possible retaliation.

Getachew said the push into Lalibela was part of a bid to secure roads in northern Amhara and prevent pro-government forces from regrouping.

"You see, we are under siege. We are under blockage. Anything that Abiy is going to use to maintain its chokehold on our people, we'll make sure it doesn't pose a serious problem," he said.

Getachew reiterated his position that the TPLF does not have designs on holding territory in Amhara and Afar and is instead focused on facilitating aid access.

The government, meanwhile, says a unilateral ceasefire it announced in late June was intended to allow aid to go in, and that the TPLF's subsequent offensive undermines that effort.