The vice-president of Burundi's constitutional court -- which was about to decide on the legality of a hugely contested third term for President Pierre Nkurunziza -- fled the country Monday.

His dramatic departure comes only hours after police shot dead four protesters in the central African country where violence has left at least 13 dead in just over a week.

Judge Sylvere Nimpagaritse told AFP that the court's judges had come under "enormous pressure and even death threats" from senior figures, which he refused to name, to rubberstamp the disputed candidature of the president.

Nimpagaritse claimed that a majority of the court's seven judges believed it would be unconstitutional for Nkurunziza to stand again, but had faced "enormous pressure and even death threats" to force them to change their mind.

Nkurunziza, a former rebel leader from the Hutu majority who has been in power since 2005, has come under intense international pressure to withdraw from the June 26 presidential poll.

US Secretary of State John Kerry warned Monday that he was "deeply concerned" about Nkurunziza's decision to stand again, which he said "flies directly in the face of the constitution".

Burundi's senate -- controlled by the president's CNDD-FDD party -- had asked the court to decide the issue last week and it was to pronounce before Saturday, when the list of candidates were to be published.

"In my soul and conscience I decided not to put my signature to a ruling, a decision which is clearly not lawful that would be imposed from the outside, and which has nothing legal about it," Nimpagaritse told AFP before leaving the country.

- 'Judges were scared' -

Burundi, where a 13-year civil war between Tutsis and Hutus ended only in 2006, has been rocked by violent protests since the CNDD-FDD designated Nkurunziza to stand in apparent defiance of the constitution and the Arusha accords which ended the war.

Police said 15 officers were wounded in Monday's clashes after a grenade was "thrown by protesters", while Burundi's Red Cross said 46 protesters were wounded. An AFP reporter saw at least eight with bullet wounds.

"I am killed by Nkurunziza!" one injured man screamed, as he was taken to hospital with a bullet wound to his shoulder.

Witnesses said other protesters had been shot, with police apparently giving no warning before opening fire with live ammunition.

Nkurunziza's supporters say he is eligible to run again since his first term in office followed his election by parliament -- not directly by the people as the constitution specifies.

But according to Nimpagaritse, only a minority of the constitutional court judges agreed until they came under intense pressure after they met on April 30.

"Two who had held that a third mandate would violate the Arusha accords and the constitution were scared" and changed their mind, he told AFP, his voice trembling and tears in his eyes.

"They told me that if we didn't change our minds we would humiliate the president and that we were taking a big risk, that we were risking our lives and we would have to join the other side," he added.

Since the protests started, the army has regularly come between police and demonstrators to avoid further clashes, and the protesters believe the soldiers are neutral.

Scores of demonstrators have been wounded since the protests began nine days ago. Nearly 600 people have also been arrested, according to police, with reports of many being beaten in custody.

- 'Army divided' -

"We have two camps fixed in their positions -- and no one is willing to back down," a diplomatic source told AFP.

The government linked a grenade attack that killed three people, including two police officers, in the early hours of Saturday to the opposition protests and branded the demonstrators "enemies of the state".

It has threatened a major crackdown, with the security minister warning the police would do anything to stop an uprising.

But the country's powerful security forces appear divided over Nkurunziza's bid to hold onto power.

On Sunday, the army's chief of staff General Prime Niyongabo said the military "remains and will remain a republican and loyalist army that is respectful of the laws and rules of Burundi and of those who govern it".

A day earlier, however, Defence Minister General Pontien Gaciyubwenge declared the army's neutrality and called for an end to attacks on citizens' rights.
Source: AFP