Image copyright AFP Image caption Former Somaliland leader Abdulahi Osman Jawari said TPLF is “trying to buy time in the same old way they have been doing in the past 10 years”.
The ex-spokesman for Ethiopia’s ruling party accused its current leader of never being interested in the peace process.
The prime minister has ordered Ethiopia’s TPLF party to form a national unity government.
Wednesday’s announcement follows fighting between Ethiopia’s eastern Tigray region and Eritrea.
But TPLF spokesman Birtukan Midekssa said the invitation was conditional on the region maintaining regional independence.
He said the premier had only asked his party to form a unity government, and had “never shown any interest in the peace process”.
Mr Midekssa said TPLF was not willing to co-operate with the prime minister, who had been in office for less than a year.
Image copyright Reuters Image caption Ethiopia faces volatile security issues in its border regions
The announcement of a unity government came just hours after the ruling EPRDF announced that the Tigrayan People’s Liberation Front, or TPLF, and an ethnic Somaliland opposition party agreed a joint opposition front for parliamentary elections in November 2019.
The TPLF party had never allowed Mr Osman Jawari, a former president of Somalia, to run for president in Ethiopia, after he accused the party of being a proxy for Ethiopia’s military and government.
Mr Midekssa was no longer a spokesman, but had always been a driving force in the TPLF party, reports the BBC.
Ethiopia and Eritrea have fought for several years over who controls the disputed border town of Badme.
Mr TPLF governs Tigray region in eastern Ethiopia, a stronghold of the Tigray People’s Liberation Front and a base for the Ethiopian military.
He said the prime minister’s stance was “irrational” and that Mr Jawari’s leadership had brought a “united, multi-ethnic” party.
On Friday, Eritrea announced that it had won a diplomatic victory by persuading the international community to place the Badme issue in the hands of arbitration.
Ethiopia was the only country not to participate in a peace process in which Eritrea’s UN ambassador brokered the talks between the two countries.
Kutum Ueker, from Ethiopia’s anti-TPLF coalition, urged the ruling party to be more sincere about coming to an agreement.
“In this situation, Birtukan said he wanted to go to the international court for its ruling, but then the ruling comes and the ruling’s faraway,” Mr Ueker said.
His comments came after Ethiopia announced it would not attend a meeting called by the president of the Somalia regional state to discuss ties with TPLF.
That region has faced a fight between TPLF and other opposition forces for control.
The opposition coalition says TPLF is trying to buy time in the same old way they have been doing in the past 10 years.
Ethiopia is the Horn of Africa’s most populous country with just over 100 million people, and the region’s second most powerful economy after South Africa.
Political instability and violent conflict have become part of the daily lives of many in the country, and many Ethiopians worry about the lack of security and more attacks on African soil.
Ethiopia’s three main ethnic groups – mainly the Diaspora, the Ogadenis and the Buaros – are all Ethiopians of Somali origin, though relations between the two countries are now improving.
Ethiopia and Eritrea fought a long and deadly war from 1998 to 2000, with the border conflict taking its toll.
The violence caused tens of thousands of civilians to flee into neighbouring Somalia for refuge, in camps that were later destroyed by armed Ethiopia and Eritrea supporters.
Eritrea has maintained that it won that war and maintains its right to exercise its own independence.
Ethiopia’s prime minister, Abiy Ahmed, arrived in London on Tuesday to meet senior British politicians including Foreign Secretary Jeremy Hunt and Prime Minister Theresa May.
It is believed the visit will also focus on the need for Ethiopia to rid its borders of all illegal miners from Libya, as agreed by London at an EU summit in May.