Nigeria’s Senate will hold an emergency session on Tuesday over the suspension of the country’s most senior judge by President Muhammadu Buhari, an official said on Sunday.

Buhari has come under increasing local and international pressure since Friday, when he suspended Justice Walter Onnoghen pending the determination of his corruption trial on charges which he disputes.

The European Union (EU), United States (US) and Britain have expressed concern over the suspension in the build up to the February election when Buhari is seeking re-election after first coming to power in 2015 with a pledge to fight corruption.

Onnoghen, who heads the Supreme Court, is accused of not disclosing money in several bank accounts. Buhari’s critics accuse him of trying to manipulate the judiciary because the Chief Justice would have been a key figure in any court ruling on a dispute in the February election.

“The Senate will reconvene on Tuesday because it considers the suspension of the Chief Justice as a national emergency,” says an aide to Senate President Bukola Saraki.

Analysts believe the Onnoghen issue could worsen the frosty relations between the Senate and the presidency, since Saraki became Senate president in defiance of the ruling party’s choice.

The Senate went into recess last week to enable senior lawmakers to take part in the February 16 presidential and parliamentary polls. The Nigerian leader has also accused the top judge of frustrating the fight against graft by freeing many suspects facing trial.

The Nigerian Bar Association (NBA), the umbrella body of lawyers, also condemned the president’s intervention, accusing Buhari of an ‘attempted coup against the Nigerian Judiciary’.

In a statement issued Friday, it appealed to the national assembly to intervene to reverse the decision. The NBA said it would meet on Monday on the matter, possibly hold a protest rally in the nation’s capital Abuja.

A Lagos constitutional lawyer, Mike Ozekhome, has called for mass protests against the ouster.

“Nigerians should brace up, come out enmasse, to protest against this illegality.Nigerian lawyers and the NBA should shut down all courts in Nigeria until the CJN (Chief Justice of Nigeria) is returned to his seat,” says Ozekhome.

Buhari, a former military ruler, came to power on a vow to defeat jihadists, whose insurgency has killed more than 27,000 since 2009.

His main opponent is Atiku Abubakar, a wealthy businessman with several failed presidential bids behind him.