Work and Pensions Secretary Peter Hain is now facing two investigations after a complaint was lodged with the Westminster "sleaze" watchdog.
The probes centre on the minister failing to declare £103,000 in donations to his deputy leadership campaign.
The Electoral Commission had already been investigating the matter.Mr Hain has provided it with information about the donations made to his failed battle to become Labour's deputy leader.Now, Parliamentary Standards Commissioner, John Lyon, has received a complaint from David Davies, Tory backbench MP for Monmouth. Mr Lyon will have to decide whether an investigation into the complaint is warranted.
Sky's political correspondent Joey Jones said the parliamentary inquiry is likely to worry Mr Hain more than the commission one.He said: "The commission is not known as the most robust of bodies. The likely sanction there is that he would be wrapped over the knuckles (if wrongdoing was found)." "But, under the parliamentary investigation, if it's found he didn't declare these things on the register of members' interests he could be severely sanctioned or suspended"."It could be very damaging and embarrassing and would be difficult for him to hold on to his cabinet position", Jones added.Mr Hain has been under pressure to reveal details of any donations that were not properly declared.
£103,00 donations were undeclared. He had already admitted receiving £5,000 during the campaign from John Mendlesohn, who went on to become Gordon Brown's chief fundraiser. Mr Hain is in charge of the biggest Government department, the Department for Work and Pensions, which administers a budget of around £130bn a year. Mr Hain said in a statement blamed the pressures of his Cabinet job for his failure to declare the cash. "During this period, I gave my campaign for office within the Labour Party second priority to my government responsibilities. "I reasonably believed that the arrangements in place for my Deputy Leader campaign would be sufficient to ensure compliance with reporting requirements, but as it transpired, due to administrative failings this was not the case after early May." Along with his statement, Mr Hain released a full list of the 17 gifts which were not declared.
Letter of Resignation: