Domitien Ndayizeye, a former leader of Burundi, said President Pierre Nkurunziza should withdraw his bid for presidency in the upcoming elections, as clashes between protesters and police turned deadly in the small Central African nation Monday. In an interview with Germany’s international broadcaster, Deutsche Welle, the ex-president said the Burundian constitution clearly forbids incumbent Nkurunziza from running again.

“No, according to the peace deal reached in Arusha, which is the reference point for the new constitution, the president cannot run again,” Ndayizeye said when asked whether he thought the constitution allowed Nkurunziza’s presidential candidacy. “The reason is simple: When we drafted the Arusha peace agreement, we decided to limit the presidency to two terms. These are binding terms.”

Nkurunziza’s decision to seek re-election has triggered widespread protests in the capital of Bujumbura in recent weeks. The government of Burundi has blocked social media networks, independent radio stations and Burundian phone lines in an effort to crack down on the demonstrations.

Nkurunziza, an ex-rebel leader, took office in 2005 following a peace agreement signed in Arusha that ended 12 years of civil war. Both the Burundian constitution and the peace deal state that no president may be elected for more than two terms in office. But Burundi’s ruling party, the National Council for the Defense of Democracy-Forces for the Defense of Democracy (CNDD-FDD), said Nkurunziza's first term does not count because the former Hutu rebel leader was appointed by Parliament rather than elected.

“This is the argument with which they are trying to find their way around the Arusha agreement. If you read the document, it clearly states that no president should govern for more than two terms,” Ndayizeye said. “There is no reason to destabilize the country. Even if he believes that he only had one term in office, I don’t understand why he wants to continue down this road if people are protesting.”

Demonstrations against Nkurunziza’s bid for a third term in power entered their second week, following a two-day truce over the weekend. Hundreds of protesters clashed with police Monday in a suburb of Bujumbura amid tear gas, stun grenades and bullets. At least four protesters were killed, and dozens of others wounded, which brought the death toll to at least 13. The slain protesters were shot dead by Burundian police in Bujumbura Monday, leading human rights activist Pierre-Claver Mbonimpa told Agence France-Presse.

“It should be plain and simple, under these circumstances and in the interest of the country, why [Nkurunziza] should not run for another term,” Ndayizeye told Deutsche Welle. “The CNDD-FDD party should not support him as a candidate for juristic and constitutional reasons, and out of national interest.”

U.S. Secretary of State John Kerry warned Monday that Nkurunziza’s third term bid is unconstitutional. The CNDD-FDD confirmed on April 25 that it had nominated Nkurunziza as a candidate for the presidential election scheduled to take place June 26.

“We are deeply concerned about President Pierre Nkurunziza’s decision, which flies directly in the face of the constitution of this country,” Kerry said in a statement in the Kenyan capital of Nairobi. “It is my understanding that an African Union delegation will go there soon to meet with him to try to underscore the importance … of the constitution of the country.”

Nkurunziza was elected by Parliament in 2005 because the unstable country was unable to hold direct elections at the time, Ndayizeye said. “Many Burundians had fled the country, and what was left were the armed groups. Burundian people also had no experience in direct elections, and the peace mediators in Arusha were worried about a possible outbreak in ethnic violence. That is why we decided to hold the first elections after the transitional period indirectly, through Parliament,” he told Deutsche Welle on Monday.

Ndayizeye, who was president of Burundi from 2003 to 2005, was selected as the presidential candidate of the National Rally for Change. He said the political party was holding talks with other opposition parties to form a larger coalition.