British companies employing hundreds of thousands of people could face a multibillion pound pensions headache if Scotland votes to split from the UK in a referendum to be held next week.

European Union rules forbid pension funds with members in two different EU countries from running a deficit. If Scotland splits from the UK and becomes an independent EU state, the pension schemes of many large companies with employees on both sides of the border would fall afoul of EU law, leaving companies needing to plug substantial holes in their pension funds.