Johnson has not ruled out return to the front line

He broke his silence after a tumultuous week in which he quit as Shadow Chancellor following reports his wife had an affair with one of his personal protection officers,

The Hull West and Hessle MP also refused to rule out a return to the front bench, although he said it was not something he was considering at the moment.

Speaking about his decision to quit, which shocked Westminster last Thursday, Mr Johnson said: "I don't think that I could have coped properly. You know you have to do your job properly. If you are trying to deal with your job as an MP, deal with your job as a front bench spokesman in the shadow cabinet and Shadow Chancellor and at the same time you have got lots of problems to sort out at home, you can't do all three.

"You have to think about that and I thought I am going to stay being a Member of Parliament. I need to sort our personal problems, so the shadow chancellor's position had to go."

Mr Johnson refused to comment on the state of his marriage, amid reports his wife has asked for a divorce. In his resignation statement he referred only to "personal issues" and said he would offer no further comment.

But since then, the Metropolitan Police has confirmed it has suspended police protection officer PC Paul Rice and launched an inquiry into an "inappropriate relationship" following allegations he had an affair with Laura, Mr Johnson's wife of 20 years. At the weekend it was claimed that Mr Johnson's secretary, Tracy Windle, also had a relationship with the same officer.

Mr Johnson, 60, had been under fire in his role as Shadow Chancellor and would have been responsible for leading Labour's attack on the coalition Government this week after worrying economic figures were released.

But he told Labour leader Ed Miliband early last week that he wanted to quit to resolve his family problems. He was replaced by Ed Balls, who spent years at Gordon Brown's side in the Treasury.

Mr Johnson, a popular figures at Westminster and among the public, has received support from colleagues and constituents.

Asked about his future plans, he said: "I will be standing again at the next election. I will put myself up for election and it is up to constituents whether or not they return me as their MP."

Mr Johnson, who held several Cabinet posts under Tony Blair and Gordon Brown, also refused to rule out a return to the front bench.

"I am not going to say never but I am not thinking about that at the moment," he said.

Asked about his recent difficulties, Mr Johnson said: I made it clear that I am not talking about my family problems.

"I am going to devote my time to my constituents and supporting my party."