Brexit supporting rebels in Prime Minister Theresa May's party made proposals on Wednesday which they said would allow trade to flow over the Irish border while safeguarding the integrity of the European Union's Single Market.
"Such measures can ensure that the trade across the Irish border is maintained," said the lawmakers from the European Research Group (ERG), a grouping in May's Conservative Party which wants a sharper break with the EU.
"The integrity of the EU Single Market is safeguarded," the lawmakers said. "The UK and the EU would be free to conclude a far-reaching Free Trade Agreement."
Both the EU and Britain want to avoid a so-called hard border between UK's Northern Ireland and the EU's Irish Republic because such a border could undermine a 1998 peace agreement that ended decades of sectarian conflict in the north.
But it is still unclear how goods crossing between the EU and the UK in Ireland would be monitored if there is no border and if Northern Ireland, as a part of the UK, leaves both the customs union and the single market.
Under the lawmakers' proposals, any additional declarations could be incorporated into the existing system used for VAT returns. They also said licensed customs brokers could be engaged to support businesses in dealing with rules of origin and customs arrangements.