Northern Ireland’s biggest political party called for a referendum on European Union membership and the easing of spending cuts as it set out its terms for supporting a minority Tory or Labour government.

The DUP, which is expected to win eight or nine MPs, also urged Westminster leaders to stand “against the tide of nationalism” in a hung parliament.

Launching its manifesto, the party’s deputy leader, Nigel Dodds, said the DUP was very likely to play a crucial role in the next Parliament. “Everyone in this room and far beyond will know just how pivotal a role we may have after this election,” he said.

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The party said it was open to a deal with Labour or the Conservatives, but has ruled out any pact with the SNP on the grounds that it would be “bad for Northern Ireland and bad for the United Kingdom as a whole”.

It supports real-terms increases in health and education and the abolition of the “bedroom tax”. The party is also seeking a feasibility study into the construction of a tunnel or bridge between Northern Ireland and Scotland and plans the devolution from London to Belfast of the power to reduce corporation tax.