First Minister and East Belfast MP Peter Robinson will face intense questions today after claims that his wife did not declare a £50,000 loan to help her toyboy lover.

Last night's BBC Spotlight programmme revealed that Strangford MP Iris Robinson secured the money from two wealthy developers, who were family friends, so 19-year-old Kirk McCambley could open a restaurant, The Lock-Keeper's Inn, in Lagan Valley Regional Park in south Belfast.

Mrs Robinson faces allegations she did not declare her financial interest in the business despite the fact that Castlereagh Borough Council, of which she is a member, awarded the tender to her teenage lover in 2008.

The programme also claimed that DUP leader Peter Robinson became aware of the situation but did not alert the appropriate watchdog bodies that his wife may have broken rules, which if found to be true, would represent clear breaches of parliamentary rules and codes.

On Wednesday Mrs Robinson, who stepped down from public life 10 days ago citing mental health problems, issued a statement admitting the affair and revealing that, racked by guilt, she had tried to take her own life in March last year.

That was four months after her fling with the former Campbell College pupil Mr McCambley ended in acrimony after the couple rowed over the repayments of the loans.

The pair had first become close after Mrs Robinson comforted Mr McCambley following the death of his father Billy, who was her friend. It is believed they started a sexual relationship in the summer of 2008.

"She looked out for me to make sure I was OK," her former lover, now 21, told last night's BBC Spotlight programme.

Selwyn Black, a former adviser to the Stranford MP, who resigned over the loans issue, told the documentary Mrs Robinson encouraged Mr McCambley to bid for the tender to run a café at the historic Lock Keeper's Cottage, a site Castlereagh Borough Council was redeveloping.

Apparently she then obtained two £25,000 payments from the developers Fred Fraser, who has since died, and Ken Campbell.

According to the programme, at the time Mrs Robinson was asking Mr Campbell for the money, she also lobbied on his behalf for one of his building projects in her parliamentary constituency of Strangford.

Mr McCambley said she had both cheques made out in his name but asked him for £5,000 back in cash. Castlereagh Borough Council subsequently awarded him the contract to run the café.

However, it is claimed that Mrs Robinson failed to register her financial interest in the scheme to her fellow councillors. She also faces claims that she did not record the two loans on her declaration of interests at Stormont and Westminster.

Mr Black, who turned whistleblower to the investigation, said the First Minister became aware of the situation and in December 2008 urged his wife to ensure both loans were repaid to Mr Campbell and the estate of Mr Fraser.

However, it is claimed that he did not alert Castlereagh Borough Council, the Stormont Assembly, Westminster or any parliamentary watchdog that his wife may have broken rules.

"They both knew the consequences of what they had been involved in and did nothing to address that circumstance," said Mr Black.

"It goes right to the heart of credibility of government in Northern Ireland."

The documentary team was told Mrs Robinson was too unwell to answer the allegations made in the programme.

Responding to the programme today, Mr Robinson said: "I completely reject BBC Spotlight's attempt to implicate me by insinuation and innuendo.

"I am even more appalled by the inclusion on that programme of comments and conclusions made without any supporting facts - indeed with facts in the programme which support a contrary position.

"While I have learned from Spotlight for the first time some alleged aspects of my wife's affair and her financial arrangements, I will be resolutely defending attacks on my character and contesting any allegations of wrongdoing. To that end, I will be addressing the media today after I have taken legal advice."