Jack Straw has said England must "be careful" in its relations with Scotland, Wales and Northern Ireland.

The justice secretary, who is responsible for constitutional affairs, told GMTV's Sunday Programme that the Union continues to provide benefits to the home nations.

Warning against Conservative calls for 'English votes on English laws', he said that with the break-up of the UK "we would all be diminished".

"England is dominant within the Union, we are over 80 per cent of the population, earn 85 per cent of the money, so we've got to be careful about how we use our power within this Union if we want this Union to continue," Straw added.

"Now, I believe that both England and Wales and Scotland benefited from the Act of Union in 1707, three centuries ago.

"I still believe that this is very strongly in Scotland's interest, Wales' interest and Northern Ireland's, but I also believe really strongly in our interests as well.

"Scottish devolution was voted on overwhelmingly by English members of Parliament. It is power devolved. It is not power, ultimately, given away. It's devolved from Westminster."

He added: "We've got to be understanding with the Scots and the Welsh. Not indulgent - I don't have any writ at all for Alex Salmond and the SNP, who want to break the Union in two."

But SNP Westminster leader Angus Robertson said: "The problem for Jack Straw is that the relationship between Scotland and England within the Union is unequal, as he himself concedes.

"That is why the best answer to the issues that he raises is a new 21st century relationship for our two nations, based upon equality of status and mutual respect.

"Scottish Independence means English Independence too - governing in the best interests of our countries, and working as partners in Europe."