Nairobi - The government of crisis-torn Burundi has approved changes to the constitution that could pave the way to a potential 14-year extension in President Pierre Nkurunziza's stay in office, senior officials said Thursday.Ministers, meeting on Tuesday in an extraordinary session, gave their agreement in principle to the proposed reforms, they said. The head of Burundi's opposition forum reacted with fury, declaring Nkurunziza had crossed a "red line" and should be chased from office.The present constitution derives from the country's 2000 peace agreement, which was signed in the northern Tanzanian town of Arusha to end a 13-year civil war that claimed more than 300 000 lives.The planned changes do not touch ethnic and gender quotas required for the government, parliament or police, "but they no longer make a reference to the Arusha peace agreement", said one of the officials, who like the other sources spoke on condition of anonymity.The Arusha accord stipulates clearly that no president can govern the country for more than 10 years.But Burundi is mired in a deep political crisis, triggered when opposition groups, determined to defend the Arusha requirement, protested against elections in 2015 that enabled Nkurunziza to stay on for a third five-year term.The victory of the 53-year-old leader plunged the central African nation into turmoil, with between 500 and 2 000 killed, according to various tolls. Nearly 400 000 have fled the country.The UN, the European Union and the African Union have previously asked the government not to step away from the Arusha agreement to avoid further inflaming the crisis.The draft constitution changes say "the president of the republic is elected for a seven-year term which is renewable" but adds, "no president can govern for more than two consecutive terms".In theory, this could mean that Nkurunziza could be elected in 2020 and be re-elected seven years later, together making a 14-year additional run.In December last year, Nkurunziza indicated he could run again in 2020 "if the people request it". 'Red line' Charles Nditije, president of an umbrella group called CNARED that includes most of the country's opposition, said Nkurunziza had taken an irreversible step."Pierre Nkurunziza has just definitively buried the Arusha peace accord," he told AFP."This is the red line that should not have been crossed... We consider this to be a declaration of war against the Burundian people, who now have no other choice than to chase out this dictator."A diplomatic observer, when questioned by AFP, said Nkurunziza was "rushing ahead", exploiting divisions within the international community to strengthen his grip.The draft text also sets down a significant change to government structure, creating the post of a vice president tasked with "assisting" the head of state.The vice president will come from an ethnic group and party that differ from those of the president, but will not wield significant powers. At present, there are two vice presidents, who come from different ethnicities, who also do not have real power.Under the new constitution, a post of prime minister will be created, drawn from the party which wins the election, and this individual will also be head of government. At present, the head of state is also head of government.The constitutional draft would also scrap a current ban on any party holding more than 80% of the seats in the National Assembly, regardless of their electoral score.Another source said that the ministers also agreed that the draft constitutional text - the fruit of a year-long consultation exercise that drew in proposals from 26 000 people - would be submitted to a referendum "very quickly, probably in February next year".