The leader of Ethiopia's rebellious northern forces said on Monday he was still fighting close to the regional capital of Mekelle after it was captured by government troops.

Debretsion Gebremichael, who heads the Tigray People's Liberation Front (TPLF), also told Reuters in a text message that some Eritrean soldiers fighting alongside the Ethiopian federal forces had been taken prisoner by his side.

Billene Seyoum, the spokeswoman for the Prime Minister Abiy Ahmed, told Reuters that responding to "delusions of a criminal clique" was not the government's focus.

There was no immediate comment from the Eritrean government, though at the start of the more than three-week conflict it had denied involvement.

Claims from all sides are difficult to verify since phone and internet links to Tigray region have been largely down and access tightly controlled since the war began on November 4.