Leaders of the opposition in the Democratic Republic of Congo (DRC) have paid tribute to politician Charles Mwando Nsimba, who died yesterday (12 December).

Mwando Nsimba was the president of the G7 coalition, which comprises seven of the DRC's political party leaders who were expelled from the government after addressing an open letter to Kabila, calling on him to respect the country's constitution and step down from power when his second term expires on 19 December.

The president of the National Union of Federal Democrats (Unadef) party, Mwando Nsimba died in Brussels, Belgium, following a long illness, according to an obituary published in the newspaper Forum des As by his son, MP Christian Mwando. Mwando confirmed his father had died from food poisoning.

In the wake of the news, leaders of the Congolese opposition and civil society representatives took to social media to pay tribute to the 81-year-old.

Moise Katumbi, former governor of Katanga and presidential candidate under the G7 banner, said Mwando Nsimba's death represents a great loss for the mineral-rich Congolese province of Katanga, and the DRC.

"With the death of Charles Mwando, the DRC and Katanga lose a great, fair and honest politician. His democratic struggle will overcome. May God rest his soul," Katumbi said on Twitter.

On his Twitter account, Olivier Kamitatu, the former planning minister and G7 political heavyweight, described the coalition's loss, and spoke of "great pain".

"Tonight the G7 is an orphan! Charles Mwando has left us. Our pain is great. For him, the fight continues!" Kamitatu said in a tweet.

Speaking on the behalf of his LUCHA (Lutte pour Le Changement) youth movement, prominent activist Fred Bauma, expressed his condolences to "the old" Mwando Nsimba's family, and to the G7 coalition.

"Thank you to the old [man] for supporting me during my imprisonment. May he rest in peace," Bauma, who was released in August after spending 17 months in prison on trumped-up charges.

Hailing from Mwando Nsimba's hometown of Lubumbashi, Moliere Kibande, who claims to belong to a society organisations, Mouvement Citoyen KSBL, on Twitter said: "Until the last days of his life, Charles Mwando stayed attached to democratic values by combating the dictatorship."

A G7 supporter, Nicolas Mwela, meanwhile, spoke of a "hero of the democracy and liberation of the Congolese people".

Who is Charles Mwando Nsimba?

Born on 18 October 1935 in Moba (Tanganyika Province), Mwando Nsimba held several ministerial roles for 12 years under the second Republic in various portfolios.

After a break from the political scene, the leader returned in 2006, after the election of current outgoing President Kabila, under whom he was successively minister of transports, minister of rural development (2007-2008), and defence minister in Adolphe Muzito's cabinet in 2008.

He was elected First Vice-President of the National Assembly in April 2012.

Viewed by the ruling elite as "les frondeurs" (the troublemakers), Mwando Nsimba, alongside with G7 heavyweights Kamitatu, Pierre Lumbi, Kyungu wa Kumwanza and other former government allies, decided to leave the governing coalition (majorité présidentielle, MP) in September 2015. The seven parties formed the G7, under Mwando Nsimba's leadership.

Mwando Nsimba, whose home was attacked in November as the government steadily escalated what has been branded a "campaign of intimidation", travelled to Belgium to receive medical care, and fell in a state of coma before passing away.