Ethiopia's prime minister said on Tuesday his government wanted to implement a deal restoring relations with former foe Eritrea quickly, to "make up for lost opportunities" after a two-decade military standoff.

Abiy Ahmed signed an agreement with Eritrean President Isaias Afkwerki on Monday, formally declaring the "state of war" between the neighbouring states was over.

"My government is keen to implement the terms we laid out in our Joint Declaration so as to quickly make up for lost opportunities and create even better ones for our people", Abiy said in a letter to Isaias that was posted on Twitter by Abiy's chief of staff.