The leader of Britain's opposition Labour Party on Sunday ruled out any informal deal with Scottish nationalists after a May 7 election if his party fails to win an overall majority, something he has previously declined to do.

When asked if Labour would negotiate with the Scottish nationalists after the election, Labour leader Ed Miliband told the BBC: "I'm not interested in deals no."

Miliband had already ruled out a formal coalition with the Scottish National Party, but his failure to exclude a looser arrangement - known as a 'confidence and supply' deal - had been seized upon by Prime Minister David Cameron's Conservatives.

"I want to be clear about this. No coalition, no tie-ins. I'm not doing deals with the Scottish National Party," said Miliband.

Opinion polls have consistently shown that neither the Conservatives nor Labour are likely to win an overall majority in the 650-seat Parliament.