HE is an assistant mental health nurse, a court interpreter and a minister – yet he is not fit to become a British citizen due to his “bad character”, according to government officials.

Olivier Mondeke Monongo is trusted by the NHS to work with some of Scotland’s most vulnerable patients, and by Global Language, a contractor to the Scottish Court Service providing expert interpreters in Glasgow Sheriff Court.

He is also a serving Pentecostal minister who gives services in a city church, has five children born in Scotland and plans to remain here for the rest of his life.

Yet immigration officials have rejected the Congolese national’s application for British citizenship, claiming he has failed the “good character” test by breaking a rule that prohibits unpaid work.

The decision rests on voluntary interpreting work he carried out for the British Red Cross.

He told The National: “I thought there must be a mistake.”

Mondeke Monongo, who arrived in the UK in 2002 claiming political asylum, was granted temporary leave to remain in 2010.

The time limit was lifted in 2013 and he began studying for his Life in the UK test, a critical step in gaining British citizenship.

But after passing the test, the Home Office refused to allow him to call himself “Scottish”.

He said: “I don’t have any intention to go back to Congo and all my children are born here. They have never been to Africa, they are more Scottish than Congolese. When you live in a country for a long time, you just feel like being a part of that country.”

The unpaid British Red Cross role saw Mondeke Monongo help out in the charity’s tracing service, which seeks to put asylum seekers and refugees in touch with loved ones in their home countries. He also helped users of Bridgeton Citizens Advice Bureau over language barriers.

There are strict immigration rules prohibiting asylum seekers from entering paid employment and Mondeke Monongo, from the Gorbals, maintains he received no payment for his services.

Meanwhile, official guidance laid out in 2014 states that “volunteering can be undertaken at any stage of the asylum process”, and there is no legal definition of what constitutes “bad character”.

However, an official letter states that Mondeke Monongo was not allowed to carry out unpaid work under the terms of his temporary leave to remain, and doing so meant he had failed to meet the "good character" requirement for citizenship.

The letter states: "On his IS96 it also stated that he was not allowed to enter into employment, paid or unpaid. Our records showed that Mr Monongo worked voluntary [sic] for the British Red Cross and worked voluntary [sic] for Bridgeton Citizens Advice Bureau in November 2007. Therefore, Mr Monongo had not complied with UK Immigration laws."

He said: “I feel bad because, apart from being an assistant nurse, I helped many people here in Glasgow when they came here and I am also a minister of the church. I think maybe the person who was dealing with my case didn’t know the work he was doing because if I was of bad character the Home Office would not have given me my indefinite leave to remain.”

Yesterday the Home Office refused to answer questions on the case, citing the beginning of purdah restrictions for the upcoming EU referendum. However, Mondeke Monongo’s MP Alison Thewliss has written to Home Secretary Theresa May asking her to “do the right thing” for her constituent and his family.

She said: “Denying someone British Citizenship simply for volunteering with the British Red Cross is totally and utterly nonsensical.

“When I started dealing with Olivier’s case, the charge levelled at him by the Home Office was that doing some unpaid work with a respected national charity is somehow a sign of ‘bad character’. The only sign of bad character I can see in this situation is a UK Government, headed by heartless Tory ministers, who are ideologically obsessed with implementing heavy-handed and right-wing immigration policies.”

She added: “The fundamental flaw with the Home Office’s argument is that good or bad character isn’t actually defined in law. Olivier is a pastor, volunteer and mental health nurse in our National Health Service who works hard to provide for his partner and five children. If that doesn’t meet the definition of good character, then it begs the question – what does?"

“With the stroke of a pen, Theresa May can right this wrong and allow this family to get on with their lives.”