Burundi's government said on Wednesday it would miss a last round of crisis talks in Tanzania that aimed to set up elections for 2020.
"Since October is a month of mourning in Burundi, the government has suggested that talks scheduled for October 24 be delayed," an official tweet said.
It referred to the murders of prince Louis Rwagasore on October 13, 1961, and Melchior Ndadaye, the country's first democratically elected president, on October 21, 1993.
The ruling Cndd-FDD party said Tuesday in local media that it would not participate if Burundi's government and the talks' organisers did not agree on who would "take part in a signing ceremony of a road map leading to 2020 elections".
Burundi has been gripped by political crisis since President Pierre Nkurunziza sought a third term in office in 2015, provoking severe civil unrest that has left at least 1 200 dead and displaced over 400 000 people.
The East African (EAC) bloc of countries is seeking to broker a political deal between the government and the opposition.
So far however, the government has refused to hold talks with some opposition groups that it brands terrorists, despite a mediation set up by regional countries under former Tanzanian president Benjamin Mkapa.
A source close to Mkapa told AFP "I am not very optimistic" about the chances of a meeting taking place.
Opposition leader Anicet Niyongabo of the umbrella group Cnared told AFP by phone from Arusha: "This shows again that the Cndd-FDD never intended to negotiate with the opposition to lift Burundi out of crisis."