The Arusha Agreement, mediated by South Africa, is being shrugged off as the state forbids activists from holding meetings.
The delicate power balance in Burundi, set out in peace accords mediated by South Africa, is in danger of coming undone. This follows serious political violence since the beginning of the year and attempts to change the Constitution so that President Pierre Nkurunziza can serve a third term.
After violence broke out among members of the Movement for Solidarity and Democracy (MSD) and police during a rally on March 8, 22 MSD members have now been sentenced to life in prison. Twenty-seven other protesters were sent to jail for between five and 10 years.
In February three Tutsi ministers resigned and after a stand-off with Nkurunziza, his vice-president, who is also from the Tutsi minority, was sacked.
This post of vice-president is part of the provisions in the Arusha Peace and Reconciliation Agreement of 2000, mediated initially by former president Nelson Mandela and then taken over by President Jacob Zuma, then South Africa's deputy president.
Pacifique Nininahazwe, a prominent human rights activist, speaking from Bujumbura, told the Mail & Guardian that civil society, churches and opposition parties in Burundi are extremely concerned about the closing of the political space and threats against the media and activists like himself.
He said that, although tensions between Hutus and Tutsis in the country have been minimised thanks to the power-sharing agreements, he believes the Hutu majority is again trying to exploit this in the run-up to elections in 2015.
"The situation is extremely worrying," Nininahazwe said. "It has, for example, become very difficult to hold any public meeting. When we apply for authorisation we are told we are trying to destabilise the country."
Not fully implemented
Civil society organisations have written to the mediators of the Arusha Agreement, South Africa and Tanzania, to warn them of the situation. Some of the provisions of the agreement, such as the setting up of a truth and reconciliation commission and special courts to judge past crimes, have not been fully implemented.
"We should first implement these provisions before trying to minimise Arusha," he said.
Thierry Vircoulon, project director for Central Africa of the International Crisis Group (ICG), said he believes South Africa should follow up on the situation in Burundi, which is experiencing "a return of the authoritarian state".
"It is a pity South Africa doesn't try and protect the legacy of the Arusha Agreement," he said, speaking from Nairobi.
The danger of ethnic conflict in the Great Lakes region is again under the spotlight as Rwanda on Sunday commemorates 20 years since the start of the devastating genocide that left almost a million people dead.
Burundi has the same ethnic make-up as Rwanda and hundreds of thousands of people have died since the 1970s in ethnic clashes, But the political situation has been relatively stable since the 2000 agreement.
Last week French political scientist Ivan Crouzel, deputy director of the Institute for Research and Debate on Governance, said at a conference at the South African Institute of International Affairs in Johannesburg that it is crucial for political agreements such as the Arusha Agreement to evolve over time to take into account current realities. "The Arusha Agreement will have to be renegotiated," he said.
Vircoulon said the shunning of the Arusha Agreement is evident in the politicisation of land reform and the issue of the return of refugees to reclaim their land, following the decades-long conflict.
In a report entitled "Fields of Bitterness: Restitution and Reconciliation in Burundi" the ICG warns that the land issue could lead to a revival of ethnic conflict.
Hutus who have, for example, left the country to live in refugee camps in Tanzania are now resettled on land since taken up by others, who might have been living there for a long time and have nowhere else to go.
"Burundi needs to find the right balance between restitution and reconciliation," says the report.
Virculon said the National Land Commission has recently taken a less conciliatory approach towards land restitution.
Meanwhile, the official opposition, the Union for National Progress, has also complained that the ruling National Council for the Defence of Democracy (CNDD-FDD) is trying to move away from the Arusha Agreement by trying to force constitutional changes through Parliament, which, for example, would ensure the passing of laws by a simple majority rather than the current two-thirds.
The new Constitution, which would include provision for Nkurunziza to stand for a third term, was rejected by Parliament by just one vote last week.
Nkurunziza is quite popular and the party fears that it might not win elections next year if he is not the CNDD-FDD candidate. The party is now attempting to validate his candidature through the Constitutional Court, which has the reputation of not being independent.
Attempts are also being made in neighbouring Democratic Republic of Congo to try to change the Constitution to permit President Joseph Kabila to be able to be re-elected for a third term by elections in 2016.