Mr Eastwood said: “Today people across these islands were looking for answers – Theresa May has failed that test.
“The Prime Minister should reflect on that reality rather than setting out 5 tests of her own halfway through the Brexit negotiations.
“We have now had 3 keynote speeches from Theresa May on Brexit – none of them has offered any solutions to the border question in Ireland.
“The Prime Minister’s commitment to work for a solution on the border is a belated recognition of reality, however that commitment is severely undermined in the same speech when she advocated the very same customs proposals which were widely and comprehensively dismissed last year.
“To save her the bother of searching, the SDLP is happy to restate the only solution that makes any sense.
“Northern Ireland should remain in the single market and the customs union to avoid a hard border in Ireland. To avoid a border in the Irish Sea, the island of Britain should remain in the customs union and the single market.
“This is the only solution that will stop a hard border, it is the only solution that protects businesses and workers and it is the only solution that protects the Good Friday Agreement.
“Nearly two years after the referendum result, it is the only credible solution that has ever emerged.
“Today’s speech again revealed the internal chaos at the heart of the British Government.
“The truth is that this remains a negotiation between members of the British Cabinet in London rather than a negotiation with the European Commission in Brussels.
“The British Prime Minister is more concerned with balancing the dogmas of her divided Cabinet rather than balancing the interests of our peoples.
“Faced with that vacuum of leadership and common sense, it is vital that the majority of people in Northern Ireland who voted to remain, alongside the Irish Government, stand together and stand firm to ensure that our political and economic future is not in the gift of this British Government.”