Tony Blair has urged Scots not to vote for independence and risk the world’s “most successful voluntary union between two countries”.

The 300-year-old union between England and Scotland has allowed both nations to prosper, enjoy stability and exert “astonishing” influence in the world, the prime minister wrote today.

In an article in the Telegraph ahead of May’s Scottish parliament election, Mr Blair urged voters to turn away from nationalism, claiming the arguments for independence had already been answered.

Devolution has given Scotland a voice within the union, Mr Blair wrote, while its recent economic success has dispelled any suggestion it is the “poor relation” north of the border.

“Scotland has used devolution to tackle long-standing problems and there is real pride, for example, in the way it has led Europe on smoking and public health. Devolution and Labour have delivered for Scotland – as for Wales – on education, on health, on crime and countless other areas,” he argued.

Taking unemployment and migration as key indicators of economic and social prosperity, Mr Blair argues the case for a Scottish success story.

Since 1997, 250,000 new jobs have been created north of the border, meaning Scots no longer leave home to find work, contributing to population growth. Unemployment in Scotland is now below the UK average with employment at a record high.

This economic stability, and the record investment that helped contributed it, would be threatened if Scotland was “wrenched out of the union,” Mr Blair argued.

The Scottish National Party (SNP) is currently the second largest party behind Labour in the Scottish parliament and is expected to gain on the executive after the Scottish election on May 3rd.

The latest opinion polls have shown the SNP ahead of Labour. This week SNP leader Alex Salmond warned the decision to renew Trident could further dent Labour’s performance in the election.