Sinn Féin, Fianna Fáil, Fine Gael and the Green Party have all admitted to using fake polling companies to gauge public opinion on the doorsteps.

The Green Party is the latest party to announce they may have used fake market research companies in “isolated incidents”, in a week that saw Independent.ie reveal Sinn Féin’s Eoin Ó’Broin had sent supporters posing as pollsters from a fictitious company to the doors of his constituency during his first general election victory in 2016.

“This is a common part of election practices,” Ó’Broin told Newstalk.

“It’s a standard practice in political party activity. I am aware of many instances in my own constituency where larger parties have done exactly the same thing, this is standard practice, if people knew how much a professional opinion poll costs,” he said.

Leo Varadkar then told RTÉ Radio One his party had done “something similar” in the past before he became leader, but that it may have happened since at a local level.

“Quite frankly yes…we would have done something similar, either volunteers would have been asked to do surveys door-to-door, or students would have been paid to do it, and it would have been done on a similar basis, anonymised for the purposes of polling,” Varadkar stated.

“But I can’t swear blind about local arrangements that may have been done in the past, but not during my period as leader, we’ve only ever used companies that have been above board.”

Fianna Fáil initially told Independent.ie that it “does not and is not aware of any members or candidates doing” fake polls, but last night backtracked on the statement, admitting that “we did on occasion use party members to undertake polling, and on those occasions they did pose as market researchers” prior to 2007.

This prompted Fianna Fáil’s Marc McSharry to call for the Taoiseach’s resignation, after the Sligo TD earlier accused Sinn Féin of abnormal “political behaviour” amounting to “basic subversion of the public”, and called for a Garda investigation.

The Green Party had also denied conducting fake polls earlier this week, claiming it had “never posed as a research company or organisation to conduct polling or to collect data on voters”, only to do a U-turn last night, admitting it has indeed happened among members.

The Data Protection Commissioner (DPC) has now weighed in on the controversy, telling political parties they will have to reveal if personal data was gathered during the polling, and how it was treated.