ADDIS ABABA, July 4 (Reuters) - Ethiopia"s Tigray region wants a full withdrawal of troops from Eritrea and the neighbouring state of Amhara before it can engage in any talks with the federal government about a ceasefire, it said in a statement on Sunday. The Tigray People"s Liberation Front (TPLF), the regional authority driven out last year by Ethiopian forces and troops from neighbouring Eritrea, returned to the region"s capital Mekelle on Monday to cheering crowds. Their return was followed by a unilateral declaration of a ceasefire by Prime Minister Abiy Ahmed"s government, a move dismissed by TPLF spokesperson Getachew Reda as a "joke". A statement from "The Government of Tigray", released on Sunday by Getachew, said it would accept a ceasefire in principle if there were ironclad guarantees of no further invasions but a series of other conditions would need to be met before any agreement could be formalised. "Invading forces from Amhara and Eritrea must withdraw from Tigray and return to their pre-war territories," the statement said. There was no immediate comment from the Prime Minister"s spokeswoman and the chairman of the government task-force set up to coordinate the security operation in Tigray. The TPLF dominated the central government for decades before Abiy came to power in 2018. His government has been battling the TPLF since late last year after accusing it of attacking military bases in Tigray. Thousands have been killed. More than 400,000 people in the region are now facing famine and there is a risk of more clashes in the region despite the unilateral ceasefire by the federal government, the United Nations warned on Friday. read more In its statement, the government of Tigray said it wanted unfettered access for aid into the region, as well as the full provision of essential services such as electricity, telecommunications, banking, healthcare and education. The statement said the United Nations should establish an independent body to investigate war crimes and an international entity to oversee the implementation of any ceasefire deal should be created. It also demanded the immediate release of all ethnic Tigrayan political leaders and members of the national defence force who are being held in prisons around the country.