Mid Ulster MLA Billy Armstrong said the office near Stewartstown is " very busy" and a "good flagship" for his party.

He also stated that his wife stopped receiving rental payments at the end of 2007.

"That's the way it used to be done and that has ceased," the UUP man said.

Mr Armstrong explained that the claims ended because he wanted to put more money from his MLA office cost allowance towards staffing.

He said the prefabricated constituency office was "purpose built" and is located on lawns close to his home.

"It's very busy. It's never been a nine-to-five office. There could be somebody there at 8am in the morning or 10pm at night," he stressed.

"It's a necessity in my view to have an office that is available at all times."

He added: "The road my office is on is a very busy road. It's one of those offices that everybody sees.

"It's a good flagship for the party. Other offices might be in towns where people don't really see the signs because there are that many. Our sign is there and it's very noticeable."

The Assemblyman said his Stewartstown office has proved more cost-effective and much busier than the premises he used to run in Magherafelt.

He also said that he devotes Wednesdays and Fridays to constituency business every week, and was working on constituency matters until 8pm last Saturday.

Mr Armstrong is not the only Ulster politician to have claimed rental payments for an office owned by a family member, and there is no suggestion that this practice is outside Assembly rules.

There is also no current requirement for MLAs to declare family links to constituency office ownership.

In February 2004, a spokesman for the Assembly told The Belfast Telegraph: " The rules governing claims against the office costs allowance do not specify any types of property from which the rental costs cannot be claimed."

A similar system for Westminster MPs was tightened up in 2003 following a number of controversies on office claims. The change meant MPs could only direct rental allowance towards relatives in "special circumstances" and when permission had been granted.

Assembly members can claim up to £70,000 of public money a year for office running costs, including rent, staffing, telephone bills, heating and electricity.

The figure was raised from £48,000 last year following the restoration of devolution.

Mr Armstrong said that in previous years he had to cover some of his staffing costs from his own salary. The MLA also confirmed that he employs both his wife and daughter on a part-time basis as part of his four-strong staff.