Eritrean authorities have called on their armed forces to mobilise in response to the renewed fighting in northern Ethiopia, the British and Canadian governments said.
The return to combat last month shattered a March truce and dashed hopes of peacefully resolving the nearly two-year war between Ethiopian authorities and the Tigray People's Liberation Front (TPLF).
Tigrayan authorities have since expressed readiness to hold talks led by the African Union, but the Ethiopian government has not responded publicly to the overtures, other than saying it remains "committed" to the AU-led peace process.
Both sides have accused the other of firing first, and fighting has spread from around southern Tigray to other fronts farther north and west, while also drawing in Eritrean troops who backed Ethiopian forces during the early phase of the war.
In travel advisories published late Friday, the Canadian and British governments warned their nationals in Eritrea to limit their movements following the mobilisation call.
"Local authorities have issued a general call for mobilization of armed forces in response to the conflict in northern Ethiopia," the Canadian government said.
"Additional security measures could be imposed on short notice across the country," it said.
The British advisory said the Eritrean announcement was made on Wednesday.
"You should be extra vigilant at this time," the advisory said.
Eritrea, which is one of the world's most closed states, has not commented on the reports.
Since the latest clashes broke out, Tigray has been bombed several times, with an official at Ayder Referral Hospital, the region's biggest, saying that 16 people had died in air strikes.
AFP was not able to independently verify the claims. Access to northern Ethiopia is severely restricted and Tigray has been under a communications blackout for more than a year.
The TPLF ruled Ethiopia for decades before Prime Minister Abiy Ahmed took office in 2018.
Abiy's government has declared the TPLF a terrorist group, and considers its claim to authority in Tigray illegitimate.
Abiy -- a Nobel Peace Prize laureate -- sent troops into Tigray in November 2020 to topple the TPLF, in response to what he said were attacks on federal army camps.
But the TPLF recaptured most of Tigray in a surprise comeback in June 2021.
It then expanded into the neighbouring regions of Afar and Amhara before the fighting reached a stalemate.