Opposition parties will boycott Burundi’s elections in protest at the president’s bid for a third term and on concerns that voting will not be fair, party officials said, escalating the nation’s worst political crisis since a civil war ended in 2005.

UN Secretary General, Ban Ki-moon in an estimation of the crisis has asked President Pierre Nkurunziza to consider shelving the election scheduled to begin on Monday, 29 June, with the parliamentary polls. Presidential poll will hold on 15 July and the senate election on 24 July.

Ban Ki-moon’s statement echoes concerns of Western and African nations who have also sought a delay after unrest in April sparked by Nkurunziza’s bid for a third term. All the elections have been postponed before as protests broke out over the third term bid.

There was even an aborted coup d’etat.

Nkurunziza has justified the move, which his opponents said was unconstitutional and foreign governments have criticised, on the basis of a favourable court ruling.

Almost 127,000 people, more than 1 percent of the population, have fled to neighbouring states and more are leaving, many voicing worries about possible violence during voting, the U.N. refugee agency UNHCR said.

Announcing the boycott by the group of 17 parties of the July 15 presidential election as well as a parliamentary poll scheduled for Monday, Francois Nyamoya, secretary general of the MSD party, told Reuters that voting would “not be credible.”

The dispute has plunged the poor African nation into crisis, raising concerns in a region with a history of ethnic conflict and leading some Western donors to scale back aid.

Frederic Bamvuginyumvira of the Frodebu party said his and other opposition parties opposed the new timetable that they said was drawn up without consultation, which the government denies.

He repeated calls for the ruling party’s Imbonerakure youth wing to be disarmed, echoing comments from Western and African states. The ruling CNDD-FDD denies the youths have been armed.

One of Burundi’s vice presidents, Gervais Rufyikiri, said this week he had fled the country after he was threatened for denouncing Nkurunziza’s bid, an allegation denied by the government.

Government officials have repeatedly said they would guarantee a fair vote. When opposition parties threatened a boycott in the past, it said the ruling party’s rivals were worried about losing at the ballot box and so wanted to stay away.

Opponents say the CENI election commission that will oversee voting is biased.

Two of the commission’s five members resigned after the crisis erupted, including its vice president who fled Burundi. They have since been replaced.

UNHCR offices in the region “have been noting a steady increase in arrivals of Burundi refugees” as Burundi gears up for Monday’s vote, UNHCR spokesman Adrian Edwards told a news briefing in Geneva on Friday.

“People are telling us they are fleeing the general political instability, election-related violence, armed attacks and arbitrary arrests,” he said, adding they included about 62,000 in Tanzania and 45,000 in Rwanda.

He said others were thought to have left but have not registered as refugees.