ABUJA (Reuters) - Nigeria’s main opposition party has halted its presidential election campaign for 72 hours weeks ahead of the vote in protest at the suspension of the country’s most senior judge by President Muhammadu Buhari, it said on Saturday.

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The European Union’s team observing the election that is scheduled to take place on Feb. 16, as well as the United States and Britain, expressed concern about the suspension.

Nigeria’s judiciary has helped resolve electoral disputes after past votes, some of which have been marred by violence and vote rigging. The chief justice could rule on any future dispute.

The president on Friday said he had suspended chief justice of Nigeria Walter Onnoghen who has been asked to appear before a tribunal over allegations of breaching asset-declaration rules.

Onnoghen has not responded to the charges and his lawyers say the tribunal does not have the authority to try him.

Buhari, who was a military ruler in the 1980s and voted into office in 2015, is seeking a fresh term in the upcoming election. At stake is control of Africa’s top crude oil producer and one of the continent’s biggest economies.

“In the first instance, we are suspending our campaign for 72 hours,” the PDP said in a statement.

“It is our hope that President Buhari will listen to the voice of all lovers of democracy the world over and restore democracy in Nigeria immediately and without qualifications,” it said, calling the suspension a “brazen assault on the constitution”.

Buhari said on Friday a court order from the Code of Conduct Tribunal, which is looking into the asset declaration allegations, directed him to suspend the judge.

“The EU Election Observation Mission is very concerned about the process and timing of the suspension of the Chief Justice of Nigeria,” the EU observers said in an emailed statement.

“The timing, just before the swearing in of justices for Electoral Tribunals and the hearing of election-related cases, has also raised concerns about the opportunity for electoral justice,” it said.

Britain’s High Commission said the timing “risks affecting both domestic and international perceptions on the credibility of the forthcoming elections”, while the U.S. embassy called for issues raised by the suspension to be solved swiftly and peacefully.

The PDP postponed a rally that it was due to hold in the central city of Markudi on Saturday.

The party was in power from the start of civilian rule in 1999 until Buhari’s 2015 election victory with his All Progressives Congress (APC) party.

“It is just an excuse they are looking for in order to escape the defeat that is awaiting them,” Lanre Issa-Onilu, a spokesman for the ruling APC, said in a telephone interview when asked about the opposition’s decision to pause its campaign.

The PDP’s candidate, businessman Atiku Abubakar who served as vice president from 1999 to 2007, is the main challenger to Buhari in the upcoming poll.