Theresa May has been urged to cut Sinn Fein MPs' expenses after it emerged they have claimed more then £1m from Westminster in the last decade.
The party received £1,119,796 in 'representative money' between February 2006 and April this year, even though Sinn Fein has an abstentionist policy with its MPs refusing to take their seats in Parliament.
The House of Commons agreed to grant Sinn Fein the financial assistance in 2006.
The revelation that the party still receives around £100,000 a year on average in expenses and allowances prompted anger.
Sinn Fein said the money is needed to fund what it termed a "first-class constituency service".
But North Down MP Lady Sylvia Hermon, who obtained the figures in response to a Parliamentary question, said the government must act.
"Frankly, I believe it is totally outrageous that Sinn Fein continues to receive vast amounts of public money for their absentee MPs," she said.
"I also believe Theresa May's Conservative government should test the will of the current House of Commons on this issue and do so this autumn.
"As the composition of the House has changed radically since 2006, when Tony Blair's Government introduced the notion of representative money for absentee Sinn Fein MPs, Theresa May should give the MPs of 2017 a vote on this.
"The public are entitled to see which current MPs support the giving of thousands of pounds of taxpayers' money to MPs who refuse to take their seats at Westminster."
Sinn Fein MP for Mid Ulster, Francie Molloy, however, said it was "a lazy argument from political unionism".
"Sinn Fein go before the electorate on the basis of active abstentionism," he said. "Our MPs do not get paid by Westminster but provide excellent representation and first-class constituency service and, as part of Sinn Fein's all-Ireland team, we act on behalf of constituents at council, Stormont, the Dail and at the EU."
Responding to Lady Hermon's question, Andrea Leadsom, the leader of the House of Commons, said: "It is the Government's view that this issue is primarily a matter for the House itself to resolve."