Sinn Fein claimed £500,000 for second homes

The five MPs, who represent the political wing of the IRA, have not even taken up their Parliamentary seats and yet they have rented three London properties from the same family at rates well above the market norm.

The party's two best-known figures, Gerry Adams, the party leader, and Martin McGuinness, Northern Ireland's deputy first minister, jointly claimed expenses of £3,600 a month to rent a shared two-bedroom flat in north London. A local estate agent, who knows the properties, said a fair monthly rent for the flat would be £1,400.

Northern Ireland Deputy First Minister Martin McGuinness (L) and Sinn Fein President Gerry Adams claimed £21,000 in the last financial year

The three other Sinn Fein MPs together claimed £5,400 a month to rent a shared, modern town house, which the estate agent said would rent on the open market for around £1,800 a month. At other times some of the MPs have stayed in a third property, another two-bedroom flat.

The Telegraph has made a series of explosive revelations about MPs' expenses that have rocked Westminster, including more disclosures today about senior Labour and Conservative politicians. More details will be published over the coming days.

The five Sinn Fein MPs have claimed more than £310,000 in five years from the public purse by submitting receipts from one man, an Irish landlord living in London, and his family.

Immediate neighbours of the three north London properties, which are all part of the same development, could not recall seeing any of the five MPs when shown photographs of them.

The five MPs denied acting improperly last night. They insisted the money had been "legitimately claimed" and that they did "regularly" travel to London for work, when they used their rented properties. The MPs say their rent includes parking, housekeeping and utility bills.

However, there were calls last night for an investigation into our disclosures. Owen Paterson, the shadow Northern Ireland secretary, said: "This needs to be looked at by the House [of Commons'] authorities. Any possible breach of rules should be investigated by either the Parliamentary Standards Commissioner or the Fees' Office [responsible for finance and administration]. All MPs have to operate within the rules, or the spirit of the rules."

Mr Paterson said the rules need to be changed, and would be reformed under a Tory Government. "It is absolutely inconceivable that a Tory-dominated House of Commons is going to vote for allowances for MPs who don't turn up."

Pat Doherty

This paper's investigation revealed that some of Sinn Fein's MPs have rotated between the three properties, in some cases moving from one property to another then back to the first for no obvious reason. The MPs have submitted rudimentary rent receipts to the Commons authorities to support their expenses claims.

Neighbours of the three-storey town house where three MPs - Michelle Gildernew, Pat Doherty and Conor Murphy - claimed expenses last year, could not recognise the politicians in photographs shown to them by The Sunday Telegraph.

One resident, who did not want to be named, said that the yellow-brick house was a rental property where young professionals appeared to "come and go".

One resident, who helps run the development, said of the MPs: "They do not live here. I have never seen them, although I do recognise from the photos that they are something to do with Sinn Fein."

The Sinn Fein MPs also have identical televisions and stereo systems. Receipts submitted to the Commons authorities show that in 2004, two of the flats, each rented at the time by two of the MPs, were equipped with "Samson" 28-inch widescreen televisions, each costing £329, and DVD Sony cinema surround systems, each costing £230. The invoices were made out in the same handwriting, with one of the flats also charging for a three-seat settee, costing £795, and Venetian blinds, costing £485.

The three properties have been rented from three members of one family, which this newspaper is not naming. The landlord and his family own at least 12 properties in the area. He and his wife live in a town house close to the rented properties.

When contacted yesterday, the landlord's wife confirmed that the family owned all three properties. She said that the Sinn Fein MPs were currently renting two of the three properties, but they had also been renting the third. "They alternate [between the properties]," she said. She refused to answer any detailed questions about the rental arrangements between the family and the Sinn Fein MPs. "My husband's business affairs are his affairs," she said.

Since MPs' second-home expenses figures were first published in 2004 for the period covering 2001/2, the five MPs have claimed £437,405 under the Additional Costs Allowance (ACA) system, which helps MPs to meet the cost of running a second home, and which was last year worth up to £24,000 per MP.

The five each claimed £21,000 of ACA in the last financial year, just short of the maximum permitted.

Earlier this year, it emerged that Sinn Fein's MPs claimed a total of £662,660 of taxpayer-funded allowances in 2007/8, including travel costs, offices and staff salaries.

Conor Murphy

The Sinn Fein MPs have never taken up their seats at Westminster because it would involve swearing an oath of allegiance to the Queen. However, in 2001, as part of the Northern Irish Peace Process, they were given permission by the Government to start claiming Parliamentary expenses, prompting cries of "treason" and "shame" in the Commons when the decision was announced.

A Sinn Fein spokesman in Belfast responded to questions from The Sunday Telegraph on behalf of all five of the party's MPs. He said: "It is widely known that Sinn Fein MPs travel regularly to London on Parliamentary business and utilise the accommodation that we rent when there. We do not purchase properties at public expense and therefore do not profit from the expenses claimed as of right. The rent we pay on these properties are all inclusive of parking, utilities, housekeeping etc and therefore you are not comparing like with like."

Each MP said that he, or she, only ever claimed for one property each year: "I feel no duty to repay anything that I have legitimately claimed and to which I am entitled under the same rules as all other MPs. If the rules are changed then I will abide by the new rules."

Michelle Gildernew

"Sinn Fein is unique in that we are the only political party that voluntarily publishes our financial accounts annually in the interest of openness and transparency. If only other parties would do likewise then the public might have more confidence in their public representatives."