The United Nations and key organizations in Europe, Africa and the French-speaking world issued a rare joint statement Monday highlighting growing concern at rising political tensions in Congo ahead of elections where some fear President Joseph Kabila may try to stay in power despite being constitutionally barred from a new term.

The U.N., European Union, African Union and International Organization of La Francophonie underlined "the crucial importance of holding a successful political dialogue" with all Congolese parties that leads to a consensus on holding free, transparent and credible elections.

Congo has not had a peaceful transfer of power in its 55 years of independence.

President Joseph Kabila, who took office in 2001, is constitutionally barred from seeking another term, and has yet to comment publicly on his political future. However, the constitutional court recently ruled that he could stay in power beyond December if elections were delayed to ensure the country still has a head of state. The election commission has asked to postpone November elections.

Thousands of opposition supporters rallied two weeks ago to denounce the court's decision. Police fired tear gas on demonstrators in the capital, and there were injuries and chaos surrounding similar marches around the country.

In recent months, the United Nations has denounced what it calls arbitrary arrests of opponents and activists and the U.S. has expressed concern about legal action against pro-democracy activists.

The government issued an arrest warrant for the top opposition candidate, Moise Katumbi, on charges he hired mercenaries, a move his supporters say is aimed at derailing his bid for the presidency. Hearings were postponed after Katumbi became ill and flew to South Africa for medical treatment on May 20. He has not yet returned.

The four organizations urged the government and all political actors "to refrain from any action that could increase tensions or lead to violence," saying "restraint and the spirit of responsibility are needed" more than ever now.

They also urged all parties to co-operate with the AU's facilitator Edem Kodjo, who is trying to arrange inclusive talks on the election.

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Associated Press Writer Carley Petesch contributed to this report from Dakar, Senegal

News from © The Associated Press, 2016