This even as Buhari swore-in the acting Chief Justice of Nigeria (CJN), Justice Ibrahim Tanko before he left for Ibadan, Oyo State, to resume his re-election campaign.
The gubernatorial candidate faulted what he called "ongoing partisan diatribes" and heated controversies over what was right or not.
The United States, Britain and the European Union expressed concern on Saturday after Nigeria's president suspended the country's chief justice three weeks before the presidential election, with the US warning it could "cast a pall" over the vote in Africa's most populous nation.
"President Buhari has sent a unsafe signal to the entire world that Nigeria is no longer a democratic nation and that we have returned to the old, jaded era of military dictatorship, " he said in a statement. If you look at Section 292 of the constitution, paragraph one clearly makes provision for that where the Chief Justice is guilty of a code of conduct.
Buhari initially delayed the appointment of Onnoghen, after he became acting chief justice in November 2016.
Buhari said his suspension will continue until the case is concluded.
Speaking during the inauguration, Justice Mohammed charged the tribunal members to know that they are accountable to God under the oath they have just sworn.
Maduro rejects European demands for new election
The U.S. and many other nations argue that Maduro's re-election last May was invalid because his strongest opponents were barred from running.
"The fact that the unlawful suspension of Onnoghen was announced just as it became public knowledge that the CJN was constituting the election petition tribunals is not lost on discerning Nigerians and the global community". "This act of desperation is geared towards affecting the outcome of the elections".
Using similar language, the Nigerian Bar Association - the umbrella body for lawyers - said Buhari had mounted an "attempted coup against the Nigerian judiciary".
Abubakar called for unity amongst the judiciary, saying they should not allow the APC government turn them against yourselves.
The British High Commission also expressed "serious concern over the suspension".
Saraki, in a statement, said that the suspension was alien to the Constitution.
According to her, it was worrisome that the interference by the President in another arm of government portends dangers for the nation's democracy, and specifically, the 2019 electoral process.
Abubakar questioned why due process was not allowed to run its course and called for the global community to threaten "strong consequences" for anyone involved.