THE SNP will make a pledge to help the North of England when it launches its manifesto tomorrow (Monday, April 20).

The party will promise to be "natural allies" of MPs in the North with promises of increased spending on infrastructure, including high-speed rail.

The SNP, which is tipped to win as many as 52 seats at the General Election making it a significant force in the House of Commons, will present its eagerly awaited manifesto on Monday.

It will say: "While a strong London is good for the UK, also having a strong Cardiff, Newcastle and Leeds is even better."

Senior SNP sources said: "The North of England would be another big winner from SNP success in Scotland."

The pledge comes as David Cameron warned a deal between the SNP and Labour, which would put Ed Miliband in power, was a "frightening proposition".

According to reports, the SNP MPs would help "rebalance the UK - both politically and economically" from the dominant City of London.

Speaking on the Andrew Marr Show this morning, Mr Cameron said a Labour/SNP deal - even if it was "vote-by-vote" would wreck the country.

He said Scottish MPs would not care about what happened in England and voters would struggle to get their bypasses and hospitals built.

He said: "Frankly, this is a group of people that wouldn't care what happened in the rest of the country. The rest of the United Kingdom - England, Wales, Northern Ireland - wouldn't get a look-in."