Image copyright PA Image caption More than a third of MPs employ family members in their offices

Family members employed by MPs are paid on average £5,600 more than other staff, a watchdog has revealed.

Pay of such "connected parties" has also risen at twice the rate of other staff, the Independent Parliamentary Standards Authority (Ipsa) found.

The group called for a review of whether MPs should be allowed to employ relatives in the future, arguing jobs must not be "personal benefits".

In total, 139 MPs employ family members at a public annual cost of about £4.5m.

The review will only apply to future staffing as the Independent Parliamentary Standards Authority (Ipsa) said it would be "unfair and legally challengeable" to investigate existing contractual arrangements.

The watchdog, which is responsible for determining MPs' pay and expenses, said there was a lingering "perception of risk" about whether the taxpayer was getting value for money in terms of the number of family members and close business associates working for MPs.

After reviewing the matter in 2010, Ipsa decided against prohibiting the employment of family members, saying it did not believe the system was being abused and family members played a "valuable role" in assisting MPs - while limiting their numbers to one per MP.

'Limited controls'

The watchdog said it was still happy with the majority of contractual arrangements but believed that controls preventing the misuse of funds were "limited". Since relatives generally occupied more senior roles it found they were paid "significantly more" than other staff.

"Public concern about the employment of connected parties has remained," it said.

"In order to determine whether these constitute any grounds for concern, Ipsa would need to undertake intrusive and potentially disproportionate work to investigate the employment practices in MPs' offices.

"But, given that there remains a perception of risk to taxpayers' money, we are obliged to address it. Therefore we are consulting again on the practice, but only in respect of the employment by MPs of any new staff."

The issue will be considered as part of a wider review of business costs and expenses payable to MPs - with any change to the rules likely to take effect either next year or after the next election, scheduled for 2020.

Ipsa is also looking into the £4.4m cost of paying off staff who worked for the 182 MPs who retired at the last election or lost their seats.

While all the sums were within the rules, it expressed concern that £975,000 was paid to 125 staff who were taken on by newly elected MPs within the subsequent 10 weeks - "sometimes in the same constituency and in the same role".

As MPs are all separately self-employed, it said the election represented a "legal break" in the staffers' employment but it noted that in other areas of the public sector the rules had been changed to prevent staff from getting pay-offs if they are soon taken on in a similar field.