Image caption Mrs Foster said her party would not have any red lines

The leader of the DUP has said maintaining the union with the UK is "by far" the most important issue in the general election.

Arlene Foster said returning a majority of unionist MPs would take the idea of a "divisive and destabilising border poll off the agenda for generations".

Sinn Féin wants to bring a referendum on Irish unity within five years.

Mrs Foster said her party would not have any red lines in upcoming negotiations to restore power-sharing.

Image caption Mrs Foster set out core 'tests' for any proposed agreement

But she did set out five core "tests" to be levelled against any agreement:

Is the agreement likely to increase support for Northern Ireland's constitutional place within the UK?

Is it fully consistent with Northern Ireland remaining a full and integral part of the UK?

Is it fully compatible with British citizenship?

Will it result in better government for Northern Ireland than direct rule would provide?

Is it consistent with the mandate received by the DUP in March's assembly election?

In a speech launching the manifesto, Mrs Foster said the general election "will go go a long way towards determining whether devolution is restored, or if we are to be ruled directly from Westminster for the next five years".

Saying Northern Ireland needed one strong voice at Westminster, she urged unionists to "unite behind the strongest unionist voice available".

Image caption Mrs Foster refused to say if she would stand aside as a nominee for first minister

"Gerry Adams has declared that this election will be a barometer on Irish unity," she added.

"Let us rise to that challenge and seek to ensure that unionism still returns a majority of unionist MPs to Westminster and puts the notion of a divisive and destabilising border poll off the agenda for generations to come."

Mrs Foster refused to say if she would stand aside as a nominee for first minister - as demanded by Sinn Féin - until an inquiry over the renewable heating scandal has reported.

But she repeatedly said the issue of who leads the DUP was one for her party alone.

Image caption The manifesto also said the party would work to get best deal for Northern Ireland leaving the EU

She told party members and journalists: "I took the team into the last assembly election.

"We won that election, therefore we have the right to choose who will be the first minister.

"We don't tell Sinn Féin who they should nominate for deputy first minister."

The manifesto also says the party will: