MPs are demanding a larger expenses budget because they claim Brexit is adding to their "workloads", the official watchdog has revealed.

The Independent Parliamentary Standards Authority (Ipsa) disclosed that MPs have been lobbying for an increase in the amount they spend on employing staff.

The revelation led to warnings that the system is "open to abuse" as more than 150 MPs employ their wives, husbands and other "connected parties" as staff.

Sir Alistair Graham, the former chairman of the committee on standards in public life, said: "It is open to abuse, there has to be a guarantee of what the money is going to.

"Brexit sounds like a rather convenient argument for increasing funding, Ipsa should be very cautious about raising budgets.

"It would be quite wrong to automatically agree an increase in the staff budget if there’s a danger that some of it just goes to improve the family income rather than as a service to the public.

"I have always been opposed to MPs being automatically able to employ their spouses. All MPs positions should be subject to open competition."